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EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY i
Running head: EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY
Thesis
Submitted to the School of Health and Human Performance at Kean University in Partial
Fulfillment of the Requirement of the Degree of Master’s of Science in Exercise Science
Richard Osolinski
Advisor: Dr. Walter Andzel
Dr. Timothy Marshall
Kean University
Union, NJ
March, 2019
Faculty Advisor___________________________________Date_______________ Faculty Advisor___________________________________Date_______________
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY ii
Table of Content
Appendices ....................................................................................................................................iii List of Tables ................................................................................................................................ iv Acknowledgements..........................................................................................................................v Abstract...........................................................................................................................................vi
1. Introduction...............……………………………………………………......….......................1 Hypotheses.………….....………………………………........................….............................10 Limitations...……………......…………………………………………..................................11 Delimitations....……………....…………………………………………................................11 Operational Definitions........................……….....…………………………………...……....12
2. Review of the Literature..........................…………………………………………………....13
Biological Mechanisms.......…...……………………………………………….....................13 Effects of Resistance Training.………………………………………………........................15 Manipulation of Loads..... …………......…………………………………….........................19 Manipulation of Pair Training...........………………………………………..........................22 Manipulation of Sets/Volume .................……………………………………........................24 Manipulation of Training Frequency………………………………………...........................26 Manipulation of Rest Intervals................................................................................................29 Summary of the Review of Literature.…...……………………………….............................29
3. Methods..............……………………………………………………………..........................34
Participants…………………………………………………………….………......................34 Instrumentation.……………………………………………………………...........................34 Procedures…………………………………………………………………............................35 Testing Procedures.………………………………………………………..............................36 Statistical Analysis.…………………………………………………………..........................37
4. Results…………...………………………………………………...........................................39
Descriptive Data of Sample………...…………………………………………......................39 Comparative of..……………………………………………………………...........................40
5. Discussion.…………………………………………………………………...........................54
References ...………………………………………………………………............................60
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY iii
Appendices
A. Participant Recruitment Flyer............................................................................................71 B. Participant Consent Form..................................................................................................72 C. Participant Debriefing Form..............................................................................................76 D. PAR-Q...............................................................................................................................77 E. Borg Modified 10 Scale.....................................................................................................81
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY iv
List of Tables and Figures
Table 1. Descriptive Statistics for 12 male participants...............................................................40
Table 2. Right Pectoralis Mean and Maximum Neuromuscular Activation.................................41
Table 3. Right Triceps Mean and Maximum Neuromuscular Activation.....................................41
Table 4. Left Pectoralis Mean and Maximum Neuromuscular Activation...................................42
Table 5. Left Triceps Mean and Maximum Neuromuscular Activation.........................................42
Table 6. Mean Rate of Perceived Exertion...................................................................................42
Table 7. Within Subjects Mauchly's Test of Sphericity.................................................................44
Table 8. Multivariate Test for Within Subjects Effect....................................................................45
Table 9. Univariate Test for Right Pectoralis Mean Activation....................................................46
Table 10. Univariate Test for Right Pectoralis Max Activation....................................................46
Table 11. Univariate Test for Right Triceps Mean Activation.......................................................47
Table 12. Univariate Test for Right Triceps Max Activation.........................................................48
Table 13. Univariate Test for Left Pectoralis Mean Activation.....................................................48
Table 14. Univariate Test for Left Pectoralis Maximum Activation..............................................49
Table 15. Univariate Test for Left Triceps Mean Activation.........................................................50
Table 16. Univariate Test for Left Triceps Maximum Activation..................................................50
Table 17. Univariate test for Rate of Perceived Exertion..............................................................51
Table 18. Pair-Wise Comparison Between Sets............................................................................52
Table 19. Friedman Test for Differences in RPE between Sets ....................................................52
Table 20. Wilxocon Signed-Rank Test for Differences in RPE Between Sets................................52
Table 21. Wilxocon Signed-Rank Test for Differences in RPE Between Sets Continued........... 53
Figure 1. Post hoc Power Analysis................................................................................................53
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY v
ACKNOWLEDGEMENTS
I would first like to thank all of my participants for making this study possible and for
devoting their time and effort throughout the course of the study because it wouldn’t be possible
without them. I would also like to thank my professors within in Kean University Exercise
Science Master’s program, including Dr. Walther Andzel, Dr. Josh Palgi, Victoria Baxter M.S.,
Professor Lisa Flemings M.S, and Professor Mark Hung M.S. for supplementing my education
with their immense knowledge in the various areas of Exercise Science and assistance during my
time at Kean University. Further, I would like to thank Dr. Timothy Marshall for providing me
with the proper equipment to conduct this study and for his support through the program as well
as aiding in the formulation, structure, organization, data analysis and completion of my Master’s
Thesis. Lastly, I would like my family, friends, and amazing class mates for their support,
patience, and encouragement through this wonderful journey.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY vi
ABSTRACT
Purpose: The purpose of this study is to investigate the effects of 1-minute rest interval on
neuromuscular activation of the pectoralis major and lateral head of triceps brachii, and the rate
of perceived exertion (RPE) during the chest press exercise. Previous studies investigated upper
body and lower body exercises utilizing varying rest periods and the effects on neuromuscular
activation and ratings of perceived exertions but the research thus far has had conflicting results.
Methods: The study consisted of 2 sessions in a week period. The first session consisted of a
completing anthropometric measurements, and a one repetition bench (1RM) test. The following
session consisted of a strength training protocol (5 sets of 8 repetitions), using 40% of 1RM for
the bench-press with a 1-minute rest interval.
Results: The mean and maximum neuromuscular activity for the pectoralis major and lateral
heads of the triceps were recorded using surface electromyography, and Borg Scale for RPE. A
repeated-measures ANOVA was used for statistical analysis with a confidence level of p <.05 to
determine if there was significant difference in neuromuscular activation or RPE found during
the study.
Conclusion: A repeated-measures ANOVA showed that 1-minute rest interval caused a
significantly lower mean neuromuscular activity in the right lateral head of triceps brachii
between sets 2 and 5, p =.003. No other significant differences in mean of maximum
neuromuscular activity or RPE were found. Suggesting that the decreases in neuromuscular
activity observed during 1-minute rest interval during the bench 40% 1-RM may not be caused
by changes in neuromuscular activity (neural fatigue).
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 1
CHAPTER 1
INTRODUCTION
Strength training is effective for improving certain fitness goals, such as muscular
strength and power; there are numerous training variables can be manipulated, such as %-1RM,
paired training, volume/sets, frequency and rest time which may be the least understood in
regards to the length of rest time and the outcomes of strength training (Freitas et al., 2015;
Ratamess et al., 2012; Tibana et al, 2011; Freitas Maia et al., 2015). Muscular strength and
power are critical attributes for many athletes that allow them perform at high levels of
intensities. Muscular strength is the ability of a muscle or muscle group to generate force at
constant velocity against resistance, whereas, power refers to one’s ability to produce force at a
higher velocity over a period of time ( Haff & Dumke, 2012; Baechle & Earle 2008). Greater
muscular strength can enhance ability to generate power of an individual which can then
translate to their athletic performance. Muscular strength is strongly correlated to superior
jumping, sprinting, and sport-specific performance (Suchomel et at. 2016). However, the amount
of power generated can only be sustained for a period of time due to the intensity and duration of
exercise and the energy systems supporting the activity (Beachle & Earle, 2008).
Before power is developed, a muscle must first contract; muscle contraction may be
defined as the activation of the actomyosin complex in muscle fibers, which will initiate the
cross-bridge cycle. When activated, a muscle will either shorten, lengthen, or remain the same
length, which depends on the external load placed on the muscle in order to produce the amount
of force required per given task. The ability of muscle to respond is controlled by chemical
(neurotransmitter) stimuli, as well as Na+-K+ ATPase exchange pump and an increased
permeability to potassium. When a muscle fiber is stimulated, an action potential is generated,
which is the basic form of communication between neurons and muscle fibers. The terminal
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 2
ends of neurons release neurotransmitters in response to the frequency, magnitude, spatial
distribution of an action potential that ultimately determine the recruitment of a motor unit.
Which is comprise of a motor neuron and the muscle fibers it innervates. Electromyography
(EMG) is a tool that can be used to measure motor unit activation and recruitment by measuring
the electrical activity inside of a muscle. EMGs can measure both the frequency and amplitude
of a muscle’s electrical activity, providing information about the muscle’s electrical activity
(Broosk et al, 1995).
When a muscle cell receives an action potential, cytosolic calcium concentrations
increase; calcium will bind to troponin, exposing the myosin binding site on tropomysium,
initiating the cross bridge cycle, and thus the sliding filament theory of muscle contraction.
Adenosine Triphosphate (ATP) is the energy currency facilitates the ‘power-stroke’ of the
sliding filament theory, and thus, muscle contraction. Small quantities are readily available to
power a muscle for the first few seconds of activity. After which, ATP must be created, which
can be done so through a few different pathways: Creatine Phospate system, Glycolysis, and
Aerobic Oxidation (Broosk et al, 1995). All three energy systems are active at any given time:
however, the magnitude of the contribution of each system to overall work performance is
primarily dependent on the intensity of the activity and secondarily to duration (Beachle & Earle
2008). The energy needed to perform short-term, high-intensity powerful exercises (5 seconds to
60 seconds) is highly dependent on anaerobic energy metabolism glycolysis and primarily the
creatine phosphate system (ACSM, 2104). The creatine phosphate system transfers high-energy
phosphates from creatine phosphate to re-phosphorylated ATP from ADP which is catalyzed by
creatine kinase, ADP + CP à ATP + C. The total amount of creatine phosphate exist in large
quantities within cells and the amount ATP stored in muscles is small, thus limiting the energy
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 3
available for muscle contraction. The ATP generated is transported to muscles cells where it then
binds to the myosin-cross bridge to trigger the “power stroke” generate muscle contraction. Once
complete ATPase breaks down the ATP into ADP and Phosphate. This process will continue to
occur if free calcium is available and homeostasis maintained with in the cell (Powers &
Howley, 2018). As the duration of exercise lasts longer than 45 seconds, creatine phosphate
levels decrease causing a shift to anaerobic glycolysis which uses carbohydrates from either
glycogen from muscles or glucose and involves multiple enzymatically catalyzed reactions
resulting in the production of pyruvate which may proceed in one of two directions: Pyruvate can
be converted to lactate, ATP is resynthesized occurs faster but still limited in duration known as
fast glycolysis (anaerobic), or Pyruvate can be shuttle to the mitochondria to undergo slow
glycolysis (aerobic) which is slower but can occur for longer durations at lower intensity
(Beachle & Earle, 2008). As the intensity decreases and the duration increases, the emphasis
gradually shift to slow glycolysis and the oxidative energy system. Therefore, causing, gradual
shift from carbohydrates to fats in the form of triglycerides are also readily available for ATP
production, but their breakdown is much slower than glucose and glycogen (ACSM,2014).
However, when conditions become unfavorable such as not adequate resources to fuel the
process and or accumulation of byproduct which can negatively affect the muscles ability to
generate power, resulting in fatigue.
Fatigue is a condition in which a muscle cannot continue to produce the required energy,
which can be attributed by both a reduction in the capacity of the central nervous system to
activate muscles, central fatigue and or impaired muscle function termed peripheral fatigue
(ACSM, 2014). Fatigue is variable and can be influenced by exercise intensity, duration of the
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 4
activity, as well as the muscle composition and fitness level of the individual (Beachle & Earle,
2008; Gentil et al. 2017; Powers & Howley, 2018).
Central fatigue can be defined as a progressive, exercise-induced degradation of the
muscle voluntary activation (Boyas & Guevel, 2010). When central fatigue develops, various
biochemical processes are affected with in the nervous system hindering or disrupting the release
of neurotransmitters, decreasing motor neuron excitation, which effects the muscles ability to
maintain muscle activation (Taylor et. al, 2016). Therefore, a muscle may not be able to produce
the needed or required force.
In addition to central fatigue, a muscle may also experience peripheral fatigue, which can
be defined as the loss of contraction force or power caused by processes anywhere between
neuromuscular junction and contractile elements of the muscle (Ament & Verkerke, 2009).
Peripheral fatigue may be caused by a lack of energy resources within the muscle and the
inability to remove byproducts resulting in an accumulation of lactic acid and other metabolites
within the muscle. The accumulation waste products (H+) and various metabolites (Mg+2, and
Pi,) cause distributions in the contractile mechanism specifically affecting Ca+2 resulting fatigue
(Boyas & Guevel, 2011). The increase in waste products and metabolites affect the cross-bridge
interaction and force production. Accumulation of hydrogen ions in the sarcoplasm causing a
decrease in pH levels within the cell triggering physiological changes such as a drop in the
contractile force due to inhibition of the cross-bridges’ interaction. This accumulation triggers
impaired reuptake of calcium by the sarcoplasmic reticulum. thus contributing the extended
relaxation period after a fatiguing contraction. By reducing the amount of Ca+2 entering the cells
limits the resources needed to initiate muscle contraction (Boyas & Guevel,2011). Ca+2 is
essential in muscle contraction because it binds regulatory proteins (eg. Tropomyosin) exposing
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 5
the binding site for on actin filament allowing for the formation of actin-myosin cross bridge
resulting in muscle-shortening (Powers & Howley, 2018). Therefore, in the absence of Ca+2
molecules will prevent interaction of actin and myosin resulting in muscular fatigue.
Organic Pi is a byproduct of the phosphogen-creatine reaction. The increase organic Pi
directly affects the release of Ca+2 by activating Ca+2 channels facilitating out of the cell causing
the muscle cell to enter a tetanic state, Pi may affect ATP driven sarcoplasm reticulum uptake of
Ca+2, and lastly forming Ca+2-Pi precipitation decreasing the availability of free Ca+2.
(Westerblad et al. 2006). Therefore, decreasing the amount of Ca+2 available in the cell will
negatively active the actin-myosin cross bridge binding. The free calcium binds tropomyosin
exposing the binding site for on actin filament allowing for the formation of actin-myosin cross
bridge resulting in muscle-shortening. So if therefore, is not sufficient amount of Ca+2 muscle
contraction will not occur. Neuromuscular activity can be measured by using specialized
equipment such as electromyograms to analyze the neuromuscular activity can be valuable in
detecting abnormalities, optimal activation levels, and or motor unit recruitment patterns that are
affected when neuromuscular fatigue occurs (Jenkin et al., 2015). Thus, as neuromuscular
fatigue occurs, it will subsequently cause a decrease in muscle function diminishing
performance.
In addition, the fitness level of an individual can contribute to level of fatigue felt. Gentil
et al. (2017) investigated elbow flexor isokinetic dynamometer peak torque and fatigue index
between men and women of different fitness levels. At the conclusion of the study, the results
indicated that resistance trained males had significantly higher elbow flexion torque than non-
resistance train males and bother resistance trained and non-trained females. Also, non-resistance
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 6
trained male and females has significantly higher fatigue indexes compared to their resistance
trained counterparts (Gentil et al.,2017).
Lastly, the composition and contractile mechanism of a muscle can also play a critical
role in neuromuscular fatigue. The muscles of the human body are composed of a mixture of
muscle fibers. There are three muscle fiber types that can be found in the human muscular
system such as type 1 (slow twitch) fiber, and type-lla and type-llx (fast twitch) fiber. Type 1
fibers contain large number of oxidative enzymes, surrounded by a large number of capillaries,
increased concentration of myoglobin compared to type- fibers, allowing them to have greater
capacity for aerobic metabolism and high resistance to fatigue (Powers & Howley, 2018). Due to
the larger amounts of capillary surrounding them and greater concentration of myoglobin
allowing for great amounts of nutrients to be delivered to the muscle fibers providing them with
nutrient to perform longer duration exercise. In contrast, Type-ll fibers contain smaller number
of mitochondria, limited capacity for aerobic oxidation, less resistance to fatigue than Type-I
fibers but contain fibers rich in glycolytic enzymes which provide them with larger capacity of
anaerobic capacity (Powers & Howley, 2018). Therefore, the type of muscle fiber or composition
of a muscle will affect the level of performance. The mixture of muscle fiber types can to
influence how muscles respond to training and affect performance. Trappe et al. (2015)
performed a muscle biopsy on a world champion sprinter. Their findings showed the world
champion sprinter had a significantly higher abundance of type-llx and type-lla fibers compared
to type-1 fibers (Trappe et al.,2015). Thus signifying the higher composition of type-ll fibers
allows for greater short bouts of explosive energy required by the sport.
In summary, there may be several reason why a person cannot continue muscle work, and
thus, become fatigue. General factors that continue to fatigue include the nature of the activity
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 7
training status of the individual. But more specifically, fatigue may be due to the depletion of
key metabolites, such as creatine phosphate, muscle and liver glycogen. And blood glucose.
High levels of muscle work cannot continue without an adequate supply of these metabolites.
Fatigue may also occur because of the accumulation of metabolites. Research has demonstrated
that the accumulation of lactic acid, loss of Ca2+as well as the accumulation of Ca2+, which
impacts oxidative phosphorylation, glycolysis and excitation-contraction coupling. Fatigue may
also occur with the accumulation of H+ ions. Lastly, fatigue will occur when the muscle no
longer responds to increase stimuli, suggesting peripheral fatigue (Powers & Howley, 2018).
In addition, to gauge the level of fatigue an individual feel can be measured by The Rate
of perceived exertions (RPE) scale. The RPE scale is a frequently used quantitative measure of
perceived exertion experienced during physical activity. The two most commonly used scales of
perceived exertion in exercise are Borg’s 6–20 scale or can be modified using 0-10 and category
ratio scale (Dawes et al., 2005; Lgally et al., 2004; Lorente et al., 2016).
Further, the Borg scale ranges from 6 (no exertion) to 20 (maximal exertion) or on the
modified scale 0 (no exertion) to 10 (maximal exertion). A perceived exertion rating between 12
to 14 on the 6-20 Borg Scale, 5 to 6 on modified scale indicates that physical activity is being
performed at a moderate level of intensity. There is strong correlation between an individual’s
perceived exertion rating and the actual heart rate during physical activity; so a person's exertion
rating may provide a fairly good estimate of the actual heart rate during activity (CDC, 2105;
ACSM 2014). Therefore, properly instructing a person how to utilize the Borg Scale can give
one an idea of how hard he or she is training and whether or not to adjust the workout intensity to
ensure he or she is exercising at an appropriate level to reach their training goal. To reduce the
instances and effects of fatigue, many athletes will engage in training programs.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 8
Moreover, to reduce the instances and effects of fatigue, many athletes will engage in
training programs. Research has demonstrated strength training is effective for improving certain
fitness goals, like muscular strength and power; numerous variables can be manipulated, such as
%-1RM, paired-training, volume/sets, frequency and rest time which may be the least understood
in regards length of rest time and the outcomes of strength training (Freitas et al., 2015;
Ratamess et al., 2012; Tibana et al, 2011; Freitas Maia et al., 2015). Resistance training is
important and should implemented in an athlete’s exercise regimen. Properly training for a
specific goal such as strength and power will allow the body to gradually build up strength,
ultimately improving an athlete’s skill level improving performance. However, research
regarding the optimal rest time interval and how it affects mechanical and physiological
variables that contributing to fatigue has been inconsistent. Therefore, the purpose of this study is
to investigate the effect of 1- minute rest interval on neuromuscular activation, and rate of
perceived exertion during the chest press exercise performed at 40% 1RM. Improving our
understanding bout optimal rest period may allow for improved design of power and strength
programs
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 9
Statement of the Problem
Optimizing different training variable such as %-1RM, paired training,
volume/sets, training frequency and rest time during will influence the effectiveness of a
resistance training program that is structured around improving strength and/or power. Several
factors may be considered when developing a strength training program, such as % of one’s 1-
reptition maximum, number of sets and repetition, frequency of training, and rest time between
sets. Research has demonstrated that strength gains may be optimized when a program consist of
loads between 70% and 90% of one’s 1RM, working between 3 and 5 sets with lower repetitions
(3-5 reps) and training a minimum of two times per week (Leite et al., 2014; Mangine et al.,
2016; Arazi & Asadi, 2011; Ochi et al.,2018; Gentil et al., 2014). Research regarding the optimal
rest time interval and how it affects mechanical and physiological variables that contributing to
fatigue has been inconsistent (Marshall et al., 2012; Martorelli et al., 2012; Davo et al. 2015;
Tibana et al. 2013). However, previous research has not taken neural measurements to explore
the impact of rest time intervals on neuromuscular system. Fatigue can alter overt performance,
such that the task is performed more slowly or clumsily or even cannot be performed
successfully, or it can alter the neuromuscular activity required to perform the task and this may
be evident as increased electrical activity of the muscle (Taylor, 2016.)
Therefore, the purpose of this study is to investigate the effect of 1- minute rest interval
on neuromuscular activation, and rate of perceived exertion during the chest press exercise
performed at 40% 1RM. Improving our understanding bout optimal rest period may allow for
improved design of power and strength programs.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 10
Hypotheses
1. Performing 5 sets of 8 repetitions at 40% 1 RM, resting 1 minute between each set will
cause a significant effect in neuromuscular activation in the pectoralis major and triceps
brachii lateral head as measured by electromyography (EMG)
2. Performing 5 sets of 8 repetitions at 40% 1 RM, resting 1 minute between each set will
cause a significant effect on exertion as assessed by the RPE scale
3. Performing 5 sets of 8 repetitions at 40% 1 RM, resting 1 minute between each set will
not cause a significant effect in neuromuscular activation in the pectoralis major and
triceps brachii lateral head, as measured by electromyography (EMG)
4. Performing 5 sets of 8 repetitions at 40% 1 RM, resting 1 minute between each set will
not cause a significant effect on exertion as assessed by the RPE scale
Scope of the Study
There has been previous research on upper body and lower body exercises utilizing
varying rest periods and the effects on neuromuscular activation and ratings of perceived
exertions but the research thus far has had conflicting results. For practical application, defining
the optimal rest period between sets can be beneficial for developing a suitable training protocol.
Developing an effective training protocol can maximize muscle activation sequentially
increasing one’s performance levels. Successfully gathering information about optimal rest
period and its effects on neuromuscular response can impose significant clinical importance.
This information can be advantageous for coaches, trainers, and clinicians who wish to design
training strength and condition protocols or rehabilitative programs to optimize athletic
performance.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 11
Assumptions
1. All research conducted and review was done in an appropriate and valid manner.
2. Researcher displayed professionalism and was ethical through the duration of the study.
3. The participants were honest and accurate during any medical history, questionnaires,
and PAR-Q information that was provided to the researcher during the study.
Limitations
1. The sample is not representative of the entire Kean University student athletic population.
2. The participants have varying levels of athletic performance.
3. The participants have varying muscular strength and endurance levels.
Delimitations
1. The participant sample population was selected from male students at Kean University in
Union, New Jersey.
2. Resistance training was required
3. The participants was male.
4. The sample was be tested using the bench press exercise.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 12
Operational Definitions
Electromyography (EMG) – Graphical recording of the electrical activity of motor unit activity
in skeletal muscle (Haff & Dumke., 2012; ACSM, 2014).
Hypertrophy – Increased size of cells or of an entire tissue; muscle hypertrophy is an increase in
the size of muscle fibers or of an entire muscle (ACSM, 2014).
Motor Unit – A single somatic motor neuron and the group of muscle fibers innervated by it
(ACSM, 2014).
Muscle Fatigue – the loss of force or power out in response to voluntary effort leading to
reduced performance (ACSM, 2104).
Muscular Endurance – The muscles ability to exert submaximal forces repetitively to move a
certain load (Haff & Dumke., 2012).
Muscular Strength – The largest amount of force that a muscle or group of muscle can generate
during a single contraction (Haff & Dumke., 2012).
Neurological system – encompasses all of the muscles in the body and the nerves serving them
(Beachle & Earle, 2008).
Rate of Perceived Exertion (RPE) – subjective measurement used to monitor progress toward
maximal exertion (Haff & Dumke., 2012).
Resistance training – form of exercise using resistance that improved muscular strength and
muscular endurance (Beachle & Earle, 2008).
Rest interval – amount of time between sets during exercise ( Davo et al., 2015)
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 13
CHAPTER 2
LITERATURE REVIEW
Strength training is effective for improving certain fitness goals, such as muscular
strength and power; there are numerous training variables that can be manipulated, such as %-
1RM, paired training, volume/sets, frequency and rest time which may be the least understood in
regards to the length of rest time and the outcomes of strength training (Freitas et al., 2015;
Ratamess et al., 2012; Tibana et al, 2011; Freitas Maia et al., 2015). Muscular strength and
power are critical attributes for many athletes that allow them perform at high levels of
intensities. Muscular strength is the ability of a muscle or muscle group to generate force at
constant velocity against resistance, whereas, power refers to one’s ability to produce force at a
higher velocity over a period of time ( Haff & Dumke, 2012; Baechle & Earle 2008). Greater
muscular strength can enhance ability to generate power of an individual which can then
translate to their athletic performance. Muscular strength is strongly correlated to superior
jumping, sprinting, and sport-specific performance (Suchomel et at. 2016). However, the amount
of power generated can only be sustained for a period of time due to the intensity and duration of
exercise and the energy systems supporting the activity (Beachle & Earle, 2008).
Before power is developed, a muscle must first contract; muscle contraction may be
defined as the activation of the actomyosin complex in muscle fibers, which will initiate the
cross-bridge cycle. When activated, a muscle will either shorten, lengthen, or remain the same
length, which depends on the external load placed on the muscle in order to produce the amount
of force required per given task. The ability of muscle to respond is controlled by chemical
(neurotransmitter) stimuli, as well as Na+-K+ ATPase exchange pump and an increased
permeability to potassium. When a muscle fiber is stimulated, an action potential is generated,
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 14
which is the basic form of communication between neurons and muscle fibers. The terminal
ends of neurons release neurotransmitters in response to the frequency, magnitude, spatial
distribution of an action potential that ultimately determine the recruitment of a motor unit.
Which is comprised of a motor neuron and the muscle fibers it innervates. Electromyography
(EMG) is a tool that can be used to measure motor unit activation and recruitment by measuring
the electrical activity inside of a muscle. EMGs can measure both the frequency and amplitude
of a muscle’s electrical activity, providing information about the muscle’s electrical activity
(Broosk et al, 1995).
When a muscle cell receives an action potential, cytosolic calcium concentrations
increase; calcium will bind to troponin, exposing the myosin binding site on tropomysium,
initiating the cross bridge cycle, and thus the sliding filament theory of muscle contraction.
Adenosine Triphosphate (ATP) is the energy currency facilitates the ‘power-stroke’ of the
sliding filament theory, and thus, muscle contraction. Small quantities are readily available to
power a muscle for the first few seconds of activity. After which, ATP must be created, which
can be done so through a few different pathways: Creatine Phospate system, Glycolysis, and
Aerobic Oxidation (Broosk et al, 1995). All three energy systems are active at any given time:
however, the magnitude of the contribution of each system to overall work performance is
primarily dependent on the intensity of the activity and secondarily to duration (Beachle & Earle
2008). The energy needed to perform short-term, high-intensity powerful exercises (5 seconds to
60 seconds) is highly dependent on anaerobic energy metabolism glycolysis and primarily the
creatine phosphate system (ACSM, 2104). The creatine phosphate system transfers high-energy
phosphates from creatine phosphate to re-phosphorylated ATP from ADP which is catalyzed by
creatine kinase, ADP + CP à ATP + C. The total amount of creatine phosphate exist in large
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 15
quantities within cells and the amount ATP stored in muscles is small, thus limiting the energy
available for muscle contraction. The ATP generated is transported to muscles cells where it then
binds to the myosin-cross bridge to trigger the “power stroke” generate muscle contraction. Once
complete ATPase breaks down the ATP into ADP and Phosphate. This process will continue to
occur if free calcium is available and homeostasis maintained with in the cell (Powers &
Howley, 2018). As the duration of exercise lasts longer than 45 seconds, creatine phosphate
levels decrease causing a shift to anaerobic glycolysis which uses carbohydrates from either
glycogen from muscles or glucose and involves multiple enzymatically catalyzed reactions
resulting in the production of pyruvate which may proceed in one of two directions: Pyruvate can
be converted to lactate, ATP is resynthesized and occurs faster but still limited in duration known
as fast glycolysis (anaerobic), or Pyruvate can be shuttled to the mitochondria to undergo slow
glycolysis (aerobic) which is slower but can occur for longer durations at lower intensity
(Beachle & Earle, 2008). As the intensity decreases and the duration increases, the emphasis
gradually shift to slow glycolysis and the oxidative energy system. Therefore, causing, gradual
shift from carbohydrates to fats in the form of triglycerides are also readily available for ATP
production, but their breakdown is much slower than glucose and glycogen (ACSM,2014).
However, when conditions become unfavorable such as not adequate resources to fuel the
process and or accumulation of byproduct which can negatively affect the muscles ability to
generate power, resulting in fatigue.
Fatigue is a condition in which a muscle cannot continue to produce the required energy,
which can be attributed by both a reduction in the capacity of the central nervous system to
activate muscles, central fatigue and or impaired muscle function termed peripheral fatigue
(ACSM, 2014). Fatigue is variable and can be influenced by exercise intensity, duration of the
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 16
activity, as well as the muscle composition and fitness level of the individual (Beachle & Earle,
2008; Gentil et al. 2017; Powers & Howley, 2018).
Central fatigue can be defined as a progressive, exercise-induced degradation of the
muscle voluntary activation (Boyas & Guevel, 2010). When central fatigue develops, various
biochemical processes are affected with in the nervous system hindering or disrupting the release
of neurotransmitters, decreasing motor neuron excitation, which effects the muscles ability to
maintain muscle activation (Taylor et. al, 2016). Therefore, a muscle may not be able to produce
the needed or required force.
In addition to central fatigue, a muscle may also experience peripheral fatigue, which can
be defined as the loss of contraction force or power caused by processes anywhere between
neuromuscular junction and contractile elements of the muscle (Ament & Verkerke, 2009).
Peripheral fatigue may be caused by a lack of energy resources within the muscle and the
inability to remove byproducts resulting in an accumulation of lactic acid and other metabolites
within the muscle. The accumulation waste products (H+) and various metabolites (Mg+2, and
Pi,) cause distributions in the contractile mechanism specifically affecting Ca+2 resulting fatigue
(Boyas & Guevel, 2011). The increase in waste products and metabolites affect the cross-bridge
interaction and force production. Accumulation of hydrogen ions in the sarcoplasm causing a
decrease in pH levels within the cell triggering physiological changes such as a drop in the
contractile force due to inhibition of the cross-bridges’ interaction. This accumulation triggers
impaired reuptake of calcium by the sarcoplasmic reticulum. thus contributing the extended
relaxation period after a fatiguing contraction. By reducing the amount of Ca+2 entering the cells
limits the resources needed to initiate muscle contraction (Boyas & Guevel,2011). Ca+2 is
essential in muscle contraction because it binds regulatory proteins (eg. Tropomyosin) exposing
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 17
the binding site for on actin filament allowing for the formation of actin-myosin cross bridge
resulting in muscle-shortening (Powers & Howley, 2018). Therefore, in the absence of Ca+2
molecules will prevent interaction of actin and myosin resulting in muscular fatigue.
Organic Pi is a byproduct of the phosphogen-creatine reaction. The increased organic Pi
directly affects the release of Ca+2 by activating Ca+2 channels facilitating out of the cell causing
the muscle cell to enter a tetanic state, Pi may affect ATP driven sarcoplasm reticulum uptake of
Ca+2, and lastly forming Ca+2-Pi precipitation decreasing the availability of free Ca+2.
(Westerblad et al. 2006). Therefore, decreasing the amount of Ca+2 available in the cell will
negatively active the actin-myosin cross bridge binding. The free calcium binds tropomyosin
exposing the binding site on a actin filament allowing for the formation of actin-myosin cross
bridge resulting in muscle-shortening. So if therefore, is not sufficient amount of Ca+2 muscle
contraction will not occur. Neuromuscular activity can be measured by using specialized
equipment such as electromyograms to analyze the neuromuscular activity can be valuable in
detecting abnormalities, optimal activation levels, and or motor unit recruitment patterns that are
affected when neuromuscular fatigue occurs (Jenkin et al., 2015). Thus, as neuromuscular
fatigue occurs, it will subsequently cause a decrease in muscle function diminishing
performance.
In addition, the fitness level of an individual can contribute to level of fatigue felt. Gentil
et al. (2017) investigated elbow flexor isokinetic dynamometer peak torque and fatigue index
between men and women of different fitness levels. At the conclusion of the study, the results
indicated that resistance trained males had significantly higher elbow flexion torque than non-
resistance train males and bother resistance trained and non-trained females. Also, non-resistance
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 18
trained male and females had significantly higher fatigue indexes compared to their resistance
trained counterparts (Gentil et al.,2017).
Lastly, the composition and contractile mechanism of a muscle can also play a critical
role in neuromuscular fatigue. The muscles of the human body are composed of a mixture of
muscle fibers. There are three muscle fiber types that can be found in the human muscular
system such as type 1 (slow twitch) fiber, and type-lla and type-llx (fast twitch) fiber. Type 1
fibers contain large number of oxidative enzymes, surrounded by a large number of capillaries,
increased concentration of myoglobin compared to type- fibers, allowing them to have greater
capacity for aerobic metabolism and high resistance to fatigue (Powers & Howley, 2018). Due to
the larger amounts of capillary surrounding them and greater concentration of myoglobin
allowing for great amounts of nutrients to be delivered to the muscle fibers providing them with
nutrient to perform longer duration exercise. In contrast, Type-ll fibers contain smaller number
of mitochondria, limited capacity for aerobic oxidation, less resistance to fatigue than Type-I
fibers but contain fibers rich in glycolytic enzymes which provide them with larger capacity of
anaerobic capacity (Powers & Howley, 2018). Therefore, the type of muscle fiber or composition
of a muscle will affect the level of performance. The mixture of muscle fiber types can to
influence how muscles respond to training and affect performance. Trappe et al. (2015)
performed a muscle biopsy on a world champion sprinter. Their findings showed the world
champion sprinter had a significantly higher abundance of type-llx and type-lla fibers compared
to type-1 fibers (Trappe et al.,2015). Thus signifying the higher composition of type-ll fibers
allows for greater short bouts of explosive energy required by the sport.
In summary, there may be several reason why a person cannot continue muscle work, and
thus, become fatigue. General factors that continue to fatigue include the nature of the activity
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 19
training status of the individual. But more specifically, fatigue may be due to the depletion of
key metabolites, such as creatine phosphate, muscle and liver glycogen. And blood glucose.
High levels of muscle work cannot continue without an adequate supply of these metabolites.
Fatigue may also occur because of the accumulation of metabolites. Research has demonstrated
that the accumulation of lactic acid, loss of Ca2+as well as the accumulation of Ca2+, which
impacts oxidative phosphorylation, glycolysis and excitation-contraction coupling. Fatigue may
also occur with the accumulation of H+ ions. Lastly, fatigue will occur when the muscle no
longer responds to increased stimuli, suggesting peripheral fatigue (Powers & Howley, 2018).
To reduce the instances and effects of fatigue, many athletes will engage in training
programs. Research has demonstrated strength training is effective for improving certain fitness
goals, like muscular strength and power; numerous variables can be manipulated, such as %-
1RM, paired-training, volume/sets, frequency and rest time which may be the least understood in
regards length of rest time and the outcomes of strength training (Freitas et al., 2015; Ratamess et
al., 2012; Tibana et al, 2011; Freitas Maia et al., 2015). Resistance training is important and
should be implemented in an athlete’s exercise regimen. Proper training for a specific goal such
as strength and power will allow the body to gradually build up strength, ultimately improving an
athlete’s skill level improving performance.
One method of increasing muscular strength and power is by manipulating the load or
weight used during resistance training. Schoenfel et al. (2014) investigated muscular adaptations
to a manipulating the load utilizing during a hypertrophy training program verse a strength
training type routine in well-trained subjects. Seventeen young men were randomly assigned to
either a hypertrophy-type resistance training group that performed 3 sets of 10 repetitions with
10 repetition maximum (RM) with 90 seconds rest or a strength-type resistance training group
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 20
that performed 7 sets of 3 repetitions with 3RM with a 3-minute rest interval. The resistance
programs both contained 3 chest press variation, wide/close-grip lat pull down, and cable row,
and 3 lower body exercises: back squat, leg press and leg extension). At the conclusion of the
study, the results indicated there was a significant increase in muscular size for both training
protocols but strength training protocol had significantly higher strength gains (Schoenfel et
al.,2014). Therefore, this study suggest that a heavier load should be used to achieve an increase
in muscular strength.
Similarly, Schoenfel et al. (2015) examined the effects of low load (30% - 50% 1RM)
resistance training versus high-load (70% - 80% 1RM) resistance training on muscular
adaptations as measured by muscle thickness, muscular endurance and upper body and lower
body 1 repetition maximum in 18 well-trained male participants. Participants were pair matched
according to baseline strength and then randomly assigned to a low-load resistance routine in
which 25–35 repetitions were performed to failure per exercise or a high-load resistance routine
where 8–12 repetitions were performed per exercise (n = 12). The protocols consisted of 3 sets of
7 exercises per session consisting of flat barbell press, barbell military press, wide-grip lat pull-
down, seated cable row, barbell back squat, machine leg press, and machine leg extension. At the
conclusion of the study, the results indicated that both high-load training and low-load protocols
produced significant increases in thickness of the elbow flexors, elbow extensors and quadriceps
femoris, with no significant differences noted between groups. Also, the results suggested that
the improvements observed in back squat strength were significantly greater for high-load
protocol compared to low-load and there was a greater increase in (1RM) bench press. Upper
body muscle endurance improved to a greater extent in low-load compared to high-load
resistance protocol. Lastly, the data showed greater strength gains for high-load protocol
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 21
(Schoenfel et al., 2015) which is in agreement with the finds in Schoendel et al., 2014. Thus
suggesting that if an individual desire to increase muscular endurance, they would work with
lower-load in coupled with higher repetitions whereas if the training goal is strength, they will
work with heavier loads with lower repetitions.
Likewise, Looney et. al. (2015) investigated neuromuscular activity in vastus lateralis and
vastus medialis quadriceps and RPE during sets that differed in resistance training utilizing 50%,
70%, or 90% 1 repetition maximum during squat performance for ten resistance trained men.
The participants were in a randomized within-subject experiment consisting of 2 test visits: a
drop-set day and a single-set day using only the 50% of 1RM intensity performed to failure. At
the start of each day, subjects performed 2 submaximal repetition sets (50% 1RM 3sets of 10
repetitions and 70% 1RM 3sets of 7 repetitions). On the drop-set day, subjects performed 3
consecutive maximal repetition sets at 90%, 70%, and 50% 1RM to failure with no rest periods
in between. On the single- set day, subjects performed a maximal repetition set at 50% 1RM to
failure. The results of the study showed greater peak EMG amplitude was significantly greater in
the maximal 90% 1RM set than all other sets performed. However, the RPE did not differ over
the intensity range of loads (Looney et. al.,2015). The data showing that when muscles are
subjected to higher intensity, will causing greater neuromuscular activity resulting in increased
muscle performance.
Overall, research has demonstrated when individuals wish to increase muscular strength
and power it is important to utilize loads between 70% and 90% of one’s 1RM (Schoenfel et
al.,2014; Schoenfel et al.,2015; Looney et. al.,2015). This is because the body is being stressed
recruiting and activating the larger type II muscle fibers, which are stimulated to work when a
muscle is challenged with heavy resistance or working to fatigue. On the other hand, when an
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 22
individual wish to increase muscular endurance, decreased the load with higher repetitions
(Baechle & Earle 2008). Therefore, depending on the athletes specific training goals whether it
be to improve muscular strength or muscular endurance, manipulating the load to achieve the
desired goal.
In addition to manipulation the load that is being is lifting, one may also manipulate
training technique such as paired training. Paired set training which is characterized by
alternating exercises performed by agonist and antagonist muscles, with or without a pre-
determined rest interval which can decrease the amount of time required to perform a workout
while completing the same volume load and using paired training such as “Super Sets” and
“TRI- set” has been suggested as an efficacious method of enhancing strength (Robbins et al.
2010). Paired training can be utilized as a way to do more exercises in a given length of time.
While your muscles are recovering from one set, you are performing another exercise rather than
taking a break.
Freitas Maia et al. (2015), evaluated agonist and antagonist paired set training on
maximal repetition performance, rating of perceived exertion and neuromuscular fatigue as
measured by fatigue index. The study consisted of 2 experimental protocols which consisted of
bench press and seated row with either a 2- minute or 4-minute rest interval between the paired
set. The paired training protocol consisted of performing the bench press set to repetition failure
followed immediately by a seated row set to repetition failure utilizing 8-RM loads, respectively.
The results of the study suggest when performing paired set training, utilizing a shorter rest
interval will induce higher levels of neuromuscular fatigue as indicated by increased fatigue
indices measured by the EMG power spectrum. However, the participants that were subjected to
shorter rest interval were able to maintain their muscular strength while performing as many
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 23
repetitions as the longer rest interval (Freitas Maia et al., 2015). The results of this study suggest
that pair training during resistance training with little or no rest periods between exercises will
induce greater metabolic demands causing greater muscular fatigue. Although, paired training
may induce great neuromuscular fatigue, it has the capacity to increase muscular performance in
a shorter amount of time.
Moreover, Robbin et al. (2009), examined the chronic effects on strength and power of
performing complex training versus traditional set training using loads ranging between 3RM
and 6RM over an eight-week span. Fifteen trained males were assessed for throw height, peak
velocity, and peak power in the bench press throw and 1 RM in the bench press and bench pull
exercises using, before and after the eight-weeks. The traditional set group performed the pulling
before the pushing exercise sets with a 4-minute rest interval, whereas the complex set group
alternated pulling and pushing sets, and both protocols the exercises were performed to failure.
The result of the study indicated there were no differences in the throw height, peak velocity
between the two conditions. However, the bench pulls and bench press 1-RM increased
significantly for the complex protocol and peak power increased significantly for the traditional
protocol. In addition, utilizing the complex protocol was more time-efficient than the traditional
set with respect to development of 1-RM bench pull and bench press, peak velocity and peak
power (Robbin et al. 2009). Thus the result suggests using complex set training method would be
effective method of exercise in regards to efficiency and strength development. The results are in
agreement with the findings of Freitas Maia et al. 2015, indicating that paired training effective
method of exercise with respect to efficiency and strength development.
Furthermore, Baker & Newton (2005), investigated the effect of complex training
consisting of agonist and antagonist muscle exercises (bench press throw and bench press
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 24
throw/bench pulls) using a standard resistance of 40kg, on power output, as measured by
Plyometric Power System. The study consisted of twenty-four college rugby league players
experienced in strength training. They were randomly assigned to a control group which
performed 5 repetitions on the bench press throw with 3-minute rest and retested on bench press
throw and an agonist and antagonist group which performed 5 repetitions on the bench press
throw and then performed 8 repetitions of the prone bench pulls using 50% 1RM, rested 3-
minutes and were retested on the bench press throw. At the conclusion of the study the data
indicated the power output remained unaltered for the control group. There was significant
increase for the agonist and antagonist group suggesting alternating agonist and antagonist
muscle exercises may acutely increase power output during power training (Baker & Newton,
2005).
In summary, researcher suggests that paired-training may be an effective training method
for maintaining and improving muscular strength. In addition, it is an efficient method allowing
for greater amount of work or weight lifted in a shorter period of time (Freitas Maia et al., 2015;
Robbin et al., 2009; Baker & Newton, 2005).
A third variable that may be manipulated in a resistance training program with the goal of
improving muscular strength and power is the number of sets or volume of exercises being
performed during an exercise program. Leite et al (2014) investigate the effects of performing 1,
3 and 5-sets on measures of muscle thickness, vertical jump ability, body composition, 5-RM of
the bench press, leg press, front lat pull down and shoulder press and 20-RM of the bench press
and leg press over a 6-month period. Forty-eight Brazilian Navy School of Lieutenants with
training experience, were randomly assigned to 1-set, 3- sets, 5-sets, or control group which
performed body weight exercises such as push-ups, pull-ups, and abdominal exercises. The
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 25
training program consisted of the following weight training exercises: bench press, leg press, Lat
pull down, leg extension, Shoulder press, leg curl, biceps curl, abdominal crunch lying on the
floor and triceps extension using 8-12RM to failure with 90 seconds -120 seconds between sets
and exercises. At the conclusion of the study, the results showed the 3- and 5-sets groups had
significantly increased elbow flexor/extensor muscle thickness with the 5-SETS being
significantly great than the others. All training groups decreased percent body fat, increased fat
free mass and vertical jump ability, with no differences between groups. The 5-set group also
showed a significantly greater increase than the 1-set and 3-set group in 5RM for three of the
four exercises tested and no significant difference among groups in 5RM. The bench press 20-
RM is the 5-sets group had significantly greater increased than the 3-sets group with 1-set being
the least Lastly, the leg press 20-RM increased in all training groups, with the 5-sets group
showing a significantly greater increase than the 1-set group (Leite et al., 2014). The results
indicate that a dose response for the number of sets per exercise and a superiority of multiple sets
compared to a single set per exercise for strength gains, muscle endurance and upper arm muscle
hypertrophy.
Mangine et al. (2016) examined and compared the effect of high-volume resistance
training versus, high-intensity resistance training on improvements in muscle size and strength in
thirty-three resistance-trained men. The participants were randomly assigned to either a high-
volume, moderate-intensity group which consisted of 4 sets of 10–12 repetitions with ~70% of
1RM, 1-min rest intervals or a low-volume, high-intensity group consisting of 4 sets of 3–5
repetitions with ~90% of 1RM, 3-min rest intervals lasting 8 weeks. Pre-training and post
training assessments of lean tissue mass was assessed using dual energy x-ray absorptiometry.
Muscle cross-sectional area and thickness of the vastus lateralis, rectus femoris , pectoralis
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 26
major, and triceps brachii muscles was measured using ultrasound images, Strength was
assessed by measuring 1RM in the back squat and bench press exercises. Blood samples were
collected at baseline, immediately post, 30 min post, and 60 min post exercise at week 3 and
week 10 to assess concentration of lactate, testosterone, growth hormone, insulin-like growth
factor-1, cortisol, and insulin concentrations. The results of this study indicated high-intensity,
low-volume resistance training utilizing long rest intervals stimulated significantly greater 1RM
for bench press and lean arm mass gains compared to low- intensity, high-volume program
utilizing short rest intervals in resistance-trained men. No differences were noted in the IGF-1
and insulin responses between groups in addition to the testosterone response but elevate lactate
concentrations were found in both protocols (Mangine et al., 2016). The data suggests that
working with high-intensity resistance training scheme stimulates greater improvements in
strength and hypertrophy in resistance-trained men during a short-term training period.
In summary, research thus far shows manipulating the number of sets or volume of
exercises being performed can cause an increase in muscular strength and power during
resistance training. Specifically, When working with higher intensity such as ~90%1RM,
working between 3 and 5 sets with lower repetitions (3-5 reps) will invoke greater demands on
physiological responses, however will produce improvement in muscle performance (Leite et al.,
2014; Mangine et al., 2016).
Furthermore, manipulating training frequency is an important variable to consider while
training for strength development. Frequency can refer to the number of resistance training
sessions performed in a given period of time, as well as to the number of times a specific muscle
group is trained over a given period of time (Schoenfeld et al. 2016). It is recommended that
healthy adults train at least two to three times per week When training a muscle group it is
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 27
suggested to allow at least 48 hours until training the same muscle to allow for sufficient
recovery (ACSM 2014).
Arazi & Asadi (2011) investigated the effects of short-term equal-volume resistance
training with different workout frequency on maximal strength, endurance, and body
composition in thirty-nine novice lifters. Assessments of body composition, leg and arm
circumferences by skin fold measurement, body weight. Strength was measured by one repetition
maximum in bench and leg press and endurance as measured by bench and leg press using 40%-
60% 1RM performed to complete exhaustion and all measurements were determined pre and
post 8 weeks of training. The participants were divided into four groups; total-body resistance
training (12 exercises for one session per week), total-body resistance training (12 exercises for
two sessions per week), lower-body, upper-body, and upper-body resistance training (12
exercises for three sessions per week), and control group. Resistance training programs used
60%1RM to 80% 1RM with 1 set of 6-12 repetitions, and exercise consisted of leg press, leg
curl, leg extension, calf raise, lat pull-down, lat pull-row, bench press, pack fly, arm curl,
dumbbell arm curl, triceps push-down, and dumbbell triceps extension. At the conclusion of the
study the data indicated significant improvements in the 1RM bench and leg press across all
training groups. Also, body weight, body composition, and bench and leg press endurance
improved for all groups, but the group which trained 3x week showed greater improvements. The
group which trained 3x week group had significant improvement in arm and thigh
circumferences where the 1x week and 2x week groups had improvements in either other (Arazi
& Asadi, 2011). Thus, suggesting that when resistance training, either it be whole body or a split
body weight training routine they will produce similar results over time of training, with greater
improvements in spilt training routine.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 28
In addition, Ochi et al. (2018) examined the effects of two knee-extension training
programs using, which consisted of the same training volume but differed in training frequency.
It looked at the changes in muscle size and strength during an 11-week training and a subsequent
6-week detraining period. During a training period of 11 weeks, untrained subjects performed
knee-extension exercise at 67% of their estimated one-repetition maximum either one session per
week consisting of 6 sets of 12 repetitions per session or three sessions per week consisting of 2
sets of 12 repetitions per session. Rating of perceived exertion and muscle stiffness were
measured as an index of muscle fatigue. Muscular size was assessed with thigh circumference
and the quadriceps muscle thickness. Lastly, changes in muscle strength were measured with
isometric maximum voluntary contraction torque. At the conclusion of their study, it showed
both groups showed significant increases in thigh circumference, muscle thickness, estimated
1RM, and maximum voluntary contraction compared with baseline measurement, while RPE
during exercise was significantly higher in the 1x week group than in the 3x week group. More
importantly, there was a significantly higher maximum voluntary contraction levels for the 3x
week group compared to 1 x week group. Lastly, both groups had significant decreases in in
thigh circumference and muscle thickness from those at the end of training period, while no
significant effect of detraining was observed in MVC (Ochi et al.,2018). Thus, indicating that
utilizing the three training sessions per week with two sets are recommended for untrained
subjects to increase muscle strength while reducing fatigue levels compared to one session per
week with a comparable work load. The results from their study are in agreement with Arazi &
Asadi (2011), that increase in training frequency of 2x-3x a week, will produce great muscular
improvements when compared to lower frequency, 1x a week training protocols.
Furthermore, Gentil et al. (2014) investigated the effects of equal-volume resistance
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 29
training performed once or twice a week on muscle mass and strength of the elbow flexors in
untrained young men. Pre and post-test elbow flexors muscle thickness were measured using
ultrasound and Peak torque was assessed by an isokinetic dynamometer. Thirty men without
previous resistance training experience were divided into two groups: Group 1 trained each
muscle group only once a week and group 2 trained each muscle twice a week during 10 weeks.
Both groups performed 2 sets of 8 – 12 repetitions of the following exercises: lat pull down,
seated row, barbell bench press, seated chest press, standing barbell biceps curl, Scott bench
biceps curls, lying barbell triceps extensions and high pulley triceps extension. The weight using
as adjusted from set to set allowing participants to complete the desired repetitions range. The
data from the present study proposed that untrained men experience similar improvements in
muscle mass as well as increases in muscular strength regardless of the training frequency
(Gentil et al., 2014). Although not significant when examining the data it appears that the
individuals in the 2x week training protocol showed greater levels of improvement. Thus,
suggesting it favorable an increased training frequency for favorable strength gains.
In summary, it is recommended that healthy adults train at least two to three times per
week. When training muscle groups it is suggested to allow at least 48 hours before training the
same muscle to allow for sufficient recovery (ACSM 2014). Moreover, research has shown that
increasing resistance training frequency to 2x week or more will impose significant increases in
muscular strength and power. (Arazi & Asadi, 2011; Ochi et al.,2018; Gentil et al., 2014).
The last variable which may be manipulated in a resistance training program with the
goal of improving strength and/or power is rest time, which can be defined as the time dedicated
to recovery between sets and exercises (Grgic et al., 2017). Marshall et al. (2012) investigated
changes in motor unit recruitment, maximal force, and rate of force development and fatigue
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 30
response as measured by surface EMGs using 80% 1RM for fourteen resistance trained male
participants. The participants were subjected to various protocols with the difference between
inter-set rest, (A) 5 sets of 4 repetitions with 3-minute rest interval, (B) 5 sets of 4 repetitions
with 20-second rest interval, and rest-pause technique, repetitions performed to failure and rested
for 20s until 20 repetitions were amassed. and the effects on the back-squat. The results indicate
the rest-pause method elicited the greatest increases in motor unit recruitment for all muscle
measured during the squat exercise compared to protocol A, and protocol B, and all groups
showed a decrease in power output as measured by decreases in EMG levels. Also, the rest-
pause method showed no significant changes in EMG levels indicating that it was no more
fatiguing post-exercise than protocol A or B which did not include failure based repetitions
(Marshall et al., 2012). The data collected indicated the rest-pause method as a superior method
of training which allows for greater amount of work done in less time and facilitated an increase
in motor unit recruitment compared to protocol A and B.
Additionally, Martorelli et al. (2012) investigated rest intervals and the effects on
neuromuscular activity as measured by surface EMG and blood lactate concentration in the
Rectus Femoris, Vastus Medialis and Vastus Lateralis of twelve men performing squat training.
The protocol consisted of six sets of six repetitions using 60%1RM with rest intervals of 1-
minute, 2-minutes and 3-minutes which took place 3 to 7 days after the 1RM retest. At the
conclusion of the study, there was no significant difference between rest intervals on power
output across rest intervals. However, although not significant, there was a decrease in peak
power and average power for all rest intervals with 2-minute rest interval having the largest
decrease. Moreover, there was no significant difference in blood lactate concentration across the
rest intervals but lactate concentrations were significantly higher post-training compared to pre-
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 31
training levels (Martorelli et al., 2012). These findings are not consistant with previous findings
suggesting that independent of the increase in blood lactate, muscle power performance
remained stable. The results of this study appear to suggest that regardless of rest interval
between sets, power output was maintained during squat exercise throughout the exercise session
in twelve resistance-trained men.
Moreover, Tibana et al. (2013) examined the effect of rest interval length on smith
machine bench press on performance, muscular power, total training volume, velocity, and
ratings perceived exertion for ten recreationally trained men. The participants performed five sets
of varying repetitions using 60% of their one-repetitions maximum, with either a 1.5 minutes or
3-minute rest period between each set. The results indicated there was a significantly higher
mean, relative and peak power output, as well as higher average velocity, volume and number of
repetitions for the 3-minute rest interval compared to the 1-minute interval. (Tibana et al., 2013).
However, the researchers did not include any metabolic or neurological outcomes to enhance the
understanding as to why there may be a difference in muscular power between the two rest
intervals,
More recently, Davó et al. (2016) investigated various rest interval periods (1 minute, 2
minutes, and 3 minutes) used between bench press throw sets on mechanical and physiological-
perceptual responses during strength training session using 40% of one repetition maximum.
The mechanical outcome or power output and physiological outcomes which included fatigue
and lactate concentration. Davó et al. (2016) and colleagues found there was a significant
difference in power outputs, lactate concentration and fatigue between the three different rest
time intervals; specifically, during the 1-minute training interval showed a greater decrease in
power output accompanied by increased levels of blood lactate concentrations and increased
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 32
levels of fatigue whereas there was no difference found when comparing the 2-minute and 3-
minute rest interval group. However, Davó et al. (2016) noted that a limitation of their study as
that they did not measure neuromuscular activity during the study, which is significant because
this could provide additional insight as to if the power reduction observed in the study was also
due to neurological factors, like fatigue. Thus, future research is needed to investigate possible
neurological mechanisms that may contribute to the observed decrease in power.
Optimizing different training variable such as %-1RM, paired training, volume/sets,
training frequency and rest time during will influence the effectiveness of a resistance training
program that is structured around improving strength and/or power. Several factors may be
considered when developing a strength training program, such as % of one’s 1-reptition
maximum, number of sets and repetition, frequency of training, and rest time between sets.
Research has demonstrated that strength gains may be optimized when a program consist of
loads between 70% and 90% of one’s 1RM, working between 3 and 5 sets with lower repetitions
(3-5 reps) and training a minimum of two times per week (Leite et al., 2014; Mangine et al.,
2016; Arazi & Asadi, 2011; Ochi et al.,2018; Gentil et al., 2014). Research regarding the optimal
rest time interval and how it affects mechanical and physiological variables that contributes to
fatigue has been inconsistent (Marshall et al., 2012; Martorelli et al., 2012; Davo et al. 2015;
Tibana et al. 2013). However, previous research has not taken neural measurements to explore
the impact of rest time intervals on neuromuscular system. Fatigue can alter overt performance,
such that the task is performed more slowly or clumsily or even cannot be performed
successfully, or it can alter the neuromuscular activity required to perform the task and this may
be evident as increased electrical activity of the muscle (Taylor, 2016.)
Therefore, the purpose of this study is to investigate the effect of 1- minute rest interval
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 33
on neuromuscular activation, and rate of perceived exertion during the chest press exercise
performed at 40% 1RM. Improving our understanding about the optimal rest period may allow
for improved design of power and strength programs.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 34
CHAPTER 3
METHODS
The purpose of this study was to explore the effects of 1-minute rest interval on
neuromuscular activation, rate of perceived exertion and fatigue during the chest press exercise.
Maximizing neuromuscular activation will improve the communication between the nervous
system and musculoskeletal increasing motor unit recruit as well as increasing neural firing
patterns. Improving the nervous system and musculoskeletal system interaction in turn will
maximize performance. Determining the optimal rest interval can be beneficial for coaches,
trainers, and or clinicians who wish to construct training protocols or rehabilitative programs to
optimize athletic performance.
Participants
To be eligible, the participants had to be a male that engaged in regular physical activity,
quantified as at least 150 minutes of moderate physical activity for past 3 months, and was
between 18 - 30 years of age. The 150 minutes of physical activity consisted of a combination of
aerobic and resistance exercises. The participants were recruited from Kean University, Union,
NJ. Participants were required to complete an informed consent form, and a Physical Activity
Readiness Questionnaire (PAR-Q) to determine if the participants were qualified to exercise,
ensure their safety and have a low risk of having any medical complications.
Materials
After to the completion of the informed consent form, and the Physical Activity Readiness
Questionnaire (PAR-Q). Measurements of each participant’s height and weight were obtained
and recorded. The height, weight, percent body fat, and body mass index were assessed using
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 35
Bioelectrical impedance analysis (BIA) Tanita TBF-410GS Body Composition Analyzer Scale.
The participants were not to eat or drink within four hours the test, no exercise within twelve
hours of the test, urinate within 30 minutes of the test, not taking any diuretic medications and no
alcohol consumption with 48 hour of the test (Haff & Dumke., 2012). In addition, the
participants were instructed to remove their socks and shoes, jewelry, and anything else that
would weight them down, in order to enable the most accurate assessment.
Surface Electromyograms (EMG)
To record neuromuscular activity during this study, surface electromyogram was utilized.
The surface EMG (BTS FREEEMG 1000) probes were placed on both left and right pectoralis
major along the sternal boarder. Another set of probes were placed on the left and right lateral
head of the triceps brachii . The probe placements were selected because the pectoralis major
and triceps brachii were shown to have higher neuromuscular activity and are the more dominant
muscles during the bench press (Stastny et al., 2017).
Design and Procedure
Dynamic Warm-up
Prior to assessing muscular strength and endurance, the participants performed a 5-
minute dynamic warmup with an additional 5 minutes spent on a treadmill with a walking speed
of 2.5 – 3.0 mph. The warm- up procedure intended to prepare the body by loosening up the
joints and targeting the muscles being utilized during the study.
1RM Bench Press Test
After the dynamic warm, the participants made their way to the fitness room where they
were tested for their one repetition maximum (1RM). While performing the bench press 1RM each
participant had a spotter to provided assistance when needed. The participants were instructed to
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 36
maintain five points of contact with the floor or bench: head, shoulders and upper back, right foot,
left foot and buttocks. The participants were instructed to lower the bar in controlled manner to
touch his chest at approximately nipple height while maintaining the five points of contact and
inhale. The participant pushed the bar upward until his elbows were fully extended while
maintaining the five points of contact and exhale. The first set was considered their warm up set
and was performed with just the bar for 15 repetitions. After the warm up was completed, the load
was changed to 40% to 60% of their perceived maximum and instructed to complete 5 to 10
repetitions. The load was changed to the predetermine second-set load. Between the set the
participants were given one minute to rest. After the one-minute rest interval, the participants
performed 3 to 5 repetitions with a load that is 60% to 80% of perceived maximum. After
completion of set 3, the participants rested for three minutes while the load was changed to 90%
of perceived maximum. After the three-minute rest, the participants performed 1 repetition with
the 90% load. The participant was given a three-minute rest, while the load was increased,
depending upon how well they performed the previous attempt. If the previous set appeared
relatively easy, increase the load by 5kg to 10kg; if, however the previous attempt was difficult
increase by 1kg to 5kg. The participant continued to perform only 1 repetition until a 1 rep max
was achieved. If an attempt was unsuccessful, the load was reduced but kept above the last
successful set and given a three-minute rest until he was successful.
Testing procedure
The study consisted of 2 experimental sessions in a 1-week period. The first session
consisted of a completing necessary paper work, anthropometric measurements, and a one
repetition bench (1RM) test for bench press. The subsequent session consisted of a strength
training protocol which included 5 sets of 8 repetitions, using 40% of 1RM for the bench-press
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 37
exercise, and subjected to a 1-minute rest interval. The variables investigated during the study
were level of neuromuscular activity, rating of perceived exertion (RPE), and fatigue. All
participants were familiarized with all equipment used for testing and training, and a
familiarization session was performed during the one repetition maximum test. Furthermore, in
an attempt to avoid diurnal variation in test measures, subjects were scheduled at approximately
the same time for each testing and training session. To limit experimental variability, the same
qualified primary investigator conducted and supervised all testing sessions.
The participants performed the experimental protocol in 1 session which consisted of a 1-
minute rest interval between sets. Through each set, subjects were encouraged to press the
barbell with as much force as possible. Participants began by laying horizontally and were
instructed to maintain five points of contact with the floor or bench: head, shoulders and upper
back, right foot, left foot and buttocks. The participants were instructed to lower the bar in
controlled manner to touch his chest at approximately nipple height while maintain the five
points of contact and inhale. Lastly, participant pushed the bar upward until his elbows were
fully extended while maintaining the five points of contact and exhale. The repetition was not
counted if the barbell was not lowered touching the chest. Also, no bouncing of the barbell was
allowed. Between each set, the participant was shown a Borg 10 scale and instructed to choose a
number from 0 (no effort) to 10 (Max effort).
Statistical Analyses
All data were analyzed using the statistical software package SPSS version 22.0. A
repeated-measures ANOVA was utilized to evaluate the influence of the one-minute rest interval
on neuromuscular activity, and rate of perceived exertion during the bench press. A significance
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 38
level of p <.05 was used to determine if there was any significant difference amongst the
variables tested. In addition, a Wilks' lambda test was used to determine if there are differences
between the means and maximum of identified groups of subjects on a combination of dependent
variables. Furthermore, a Mauchly’s test for Sphericity was conducted to investigate if there
were any violations.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 39
CHAPTER 4
RESULTS
Research has demonstrated the rest time intervals affect mechanical and physiological
variables, which in turn, may reduce power output during the bench press exercise performed at
40% of the 1 repetition maximum. However, previous research has not taken neural
measurements to explore the impact of rest time intervals on neuromuscular activation. The
information gathered will enhance our understanding rest interval and the effects on
neuromuscular activation. Moreover, this will allow us to determine if the 1-minute rest interval
provides sufficient recovery time for the neuromuscular systems. The purpose of this study was
to investigate the effects of 1-minute rest interval on neuromuscular activation, during the chest
press exercise.
A repeated-measures ANOVA was utilized to evaluate the influence of the one-minute
rest interval on neuromuscular activity, and rate of perceived exertion during the bench press. All
data gathered during this study is present below in several tables and figures.
Descriptive Data of Sample
Twelve (N = 12) physical active males were recruited to participate in the present study.
All data gathered during this study is present below in several tables and figures. Table 1
displays the descriptive statistics for twelve physically activate male participants. Displays Age,
Height, Weight, Body fat%, BMI and the result from a one repetition maximum test performed.
The age for the 12 male participants ranged from 20 years of age to 28 years of age with a mean
age of 23.67 ± 2.67. The height for the 12 male participants ranged from 190.50 cm to 165.10cm
with a mean height of 175.68 ± SD 8.9. The weight for the participants ranged from 60.91Kg to
101Kg with a mean weight of 82.31kg ± 14.1. The body fat percent for the 12 male participants
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 40
ranged from 7.30% to 25.70% with a mean of 15.28% ± SD 5.23. The mean boy fat percent for
the 12 male participants is considered to be average (14.1% - 17.5%) below average (17.4% -
22.5%) categories (ASCM, 2014). Body mass index (BMI) ranged from 20.30 Kg/m2 to 33.00
Kg/m2 with mean BMI of 26.56 ± 3.84 Kg/m2. (The 1RM ranged from 65.91Kg to 136.36 Kg
with the mean 1RM 109.24 ± 21.55Kg presented in Table 1.
Table 1
Descriptive Statistics
Table 1 displays the descriptive statistics for twelve physically activate male participants.
Displays Age, Height, Weight, Body fat%, BMI and the result from a one repetition maximum
test performed.
The 12 participants completed 2 experimental sessions lasting 1-week long. During the
first session, the participants had their 1 repetition maximum (RM) were tested (Table 1). The
subsequent session consisted of a strength training protocol which included 5 sets of 8
repetitions, using 40% of 1RM for the bench-press exercise, and subjected to a 1-minute rest
interval. Surface EMG probes were placed on left and right Pectoralis Major muscles on the
sternal borders, and left and right lateral heads of the Triceps Brachii to assess neuromuscular
activity within the muscles.
Table 2 through Table 5 display the mean, maximum and standard deviations of the EMG
data for the left and right Pectoralis Major and Triceps Brachii obtained during the 5 sets.
N Minimum Maximum Mean Std. Deviation Age (Yrs.) 12 20.00 28.00 23.67 2.67
Height (Cm) 12 165.10 190.50 175.68 8.92 Weight (Kg) 12 60.91 101.59 82.31 14.14 Body Fat % 12 7.30 25.70 15.28 5.23
BMI 12 20.30 33.00 26.56 3.84 1 RM (Kg) 12 65.91 136.36 109.24 21.55
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 41
Immediately after completing the set, the participant was to rate their level exertion and
fatigue utilizing a Borg 10 scale (Table 6).
Table 2 Right Pectoralis Mean and Maximum Neuromuscular Activation
Right Pectoralis Mean Activation
(mV)
Std. Deviation
Right Pectoralis Maximum Activation
(mV)
Std. Deviation
Set 1 0.17 0.080 0.550 0.231 Set 2 0.16 0.067 0.566 0.223 Set 3 0.17 0.075 0.576 0.280 Set 4 0.16 0.070 0.570 0.226 Set 5 0.16 0.070 0.566 0.223 Table 2 displays the mean and maximum neuromuscular activation for the Right
Pectoralis Major for each set.
Table 3 Right Triceps Mean and Maximum Neuromuscular Activation
Right Triceps Mean
Activation (mV)
Std. Deviation
Right Triceps Maximum Activation
(mV)
Std. Deviation
Set 1 0.157 0.083 0.437 0.244 Set 2 0.150 0.070 0.430 0.206 Set 3 0.148 0.072 0.423 0.215 Set 4 0.143 0.062 0.400 0.172 Set 5 0.136 0.060 0.383 0.161 Table 3 presents the mean and maximum neuromuscular activation for the Right Triceps
for each set.
Table 4 displays the mean and maximum neuromuscular activation for the left pectoralis
major.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 42
Table 4 Left Pectoralis Mean and Maximum Neuromuscular Activation
Left Pectoralis
Mean Activation (mV)
Std. Deviation
Left Pectoralis Maximum Activation
(mV)
Std. Deviation
Set 1 0.140 0.065 0.497 0.244 Set 2 0.142 0.065 0.522 0.269 Set 3 0.143 0.069 0.529 0.263 Set 4 0.147 0.071 0.553 0.313 Set 5 0.146 0.073 0.519 0.260
Table 5 displays the mean and maximum neuromuscular activation for the left triceps for
each set. Table 5 Left Triceps Mean and Maximum Neuromuscular Activation
Left Triceps Mean
Activation (mV)
Std. Deviation
Left Triceps Maximum Activation
(mV)
Std. Deviation
Set 1 0.156 0.060 0.418 0.156 Set 2 0.144 0.050 0.402 0.138 Set 3 0.142 0.047 0.400 0.146 Set 4 0.138 0.044 0.391 0.121 Set 5 0.135 0.042 0.398 0.142
Table 6 shows the mean Rate of Perceived exertion for all sets performed by the twelve
male participants.
Table 6 Mean Rate of Perceived Exertion
RPE Std. Deviation Set 1 1.08 0.29 Set 2 1.58 0.79 Set 3 1.83 0.83 Set 4 2.08 0.79 Set 5 2.25 0.87
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 43
Table 7 displays the results of the Mauchly’s Test of Sphericity, which is an important
assumption of a repeated-measures ANOVA. Sphericity refers to the condition where
the variance of the differences between all possible pairs of within-subject conditions are equal.
The violation of Sphericity occurs when it is not the case that the variances of the differences
between all combinations of the conditions are equal.
Mauchly’s Test of Sphericity indicates that the assumption of Sphericity has not been
violated for right Pectoralis mean activation X2(9) = 15.61, p = .080, right Pectoralis max
activation X2(9) = 7.93, p = .55, left Pectoralis mean activation X2(9) = 12.56, p = .19, left
Triceps max activation X2(9) = 3.70, p = .93, and RPE X2(9) = 10.81, p = .30.
In addition, Mauchly’s Test of Sphericity shows that the assumption of Sphericity has
been violated for the Right Triceps mean X2(9) = 32.47, p = .000 and maximum activation X2(9)
= 29.67, p = .001, Left Pectoralis Major maximum activation X2(9) = 21.33, p = .012, and Left
Triceps mean activation, X2(9) = 31.04, p = .000. Lower-bound estimate, Greenhouse-Geisser
correction and the Huynh-Feldt correction are will be used in future tests to combat the violation
of Sphericity.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 44
Table 7 Within Subjects Mauchly's Test of Sphericity
Measure Mauchly's W
Approx. Chi-
Square
df Sig. Epsilonb Greenhouse-
Geisser Huynh- Feldt
Lower- bound
Right Pectoralis
Mean Activation
0.19 15.61 9 0.080 0.53 0.665 0.25
Right Pectoralis Max
Activation
0.43 7.93 9 0.55 0.74 1.0 0.25
Right Triceps Mean
Activation
0.032 32.47 9 0.000 0.38 0.43 0.25
Right Triceps Max
Activation
0.043 29.67 9 0.001 0.43 0.50 0.25
Left Pectoralis Mean
Activation
0.26 12.56 9 0.19 0.62 0.82 0.25
Left Pectoralis Major Max Activation
0.10 21.33 9 0.012 0.46 0.54 0.25
Left Triceps Mean
Activation
0.037 31.04 9 0.000 0.38 0.43 0.25
Left Triceps Max
Activation
0.68 3.70 9 0.93 0.82 1.0 0.25
RPE 0.32 10.81 9 0.30 0.70 0.97 0.25
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 45
Table 8 displays the results for Multivariate tests and tests of within-subjects effect for
neuromuscular activation. The multivariate test for within subject’s effect indicates that there is
a significant within-subjects effect V = 1.11, F (36,136) = 1.66, p <.05, partial h2 = .035.
Table 8 Multivariate Test for Within Subjects Effect.
Within Subjects Effect Value F
Hypothesis df
Error df Sig.
Partial Eta
Squared Noncent. Parameter
Sets
Pillai's Trace
1.11 1.66 36 156 0.020 0.28 59.57
Wilks' Lambda
0.180 2.21 36 136.65 0.001 0.35 73.44
Hotelling's Trace
3.14 3.01 36 138 0 0.44 108.28
Roy's Largest
Root 2.67 11.55 9 39 0 0.73 103.98
Follow-up Univariate tests were performed to determine within which set for a muscle
group did have a significant difference in mean or maximum EMG data occur.
Table 9 displays the result from a univariate test for within-subject effects for Right
Pectoralis mean activation. Table 9 indicates there was no significant difference in mean
neuromuscular activation for the right Pectoralis Major within the 5 sets, F (4,44) = 1.073, p =
.0381.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 46
Table 9
Univariate Test for Right Pectoralis Mean Activation
Source Measure Type III Sum
of Squares
df Mean Square
F Sig. Partial Eta
Squared
Noncent. Parameter
Pectoralis Mean
Activation
Sphericity Assumed
0.001 4 0 1.073 0.381 0.089 4.292
Greenhouse- Geisser
0.001 2.133 0 1.073 0.362 0.089 2.289
Huynh-Feldt 0.001 2.661 0 1.073 0.37 0.089 2.855
Lower- bound
0.001 1 0.001 1.073 0.323 0.089 1.073
Table 10 displays the result from a univariate test for within-subject effects for Right
Pectoralis max activation. Table 10 indicates there was no significant difference in maximum
neuromuscular activation for the Right Pectoralis Major within the 4 sets, F (4,44) = 0.247, p =
.91.
Table 10 Univariate Test for Right Pectoralis Max Activation
Source Measure Type III Sum
of Squares
df Mean Square
F Sig. Partial Eta
Squared
Noncent. Parameter
Right Pectoralis
Max Activation
Sphericity Assumed
0.004 4 0.001 0.247 0.91 0.022 0.988
Greenhouse- Geisser
0.004 2.967 0.001 0.247 0.861 0.022 0.733
Huynh-Feldt 0.004 4 0.001 0.247 0.91 0.022 0.988
Lower- bound
0.004 1 0.004 0.247 0.629 0.022 0.247
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 47
Table 11 displays the result from a univariate test for within-subject effects for Right
Triceps mean activation. Table 11 indicates there is a significant difference in mean
neuromuscular activation for the Right Triceps for within-subjects over the time of the sets, F
(1.51,16.62) = 4.54, p = .035.
Table 11 Univariate Test for Right Triceps Mean Activation
Source Measure
Type III Sum
of Squares
df Mean Square F Sig. Partial
Eta Squared
Noncent. Parameter
Right Triceps Mean
Activation
Sphericity Assumed 0.003 4 0.001 4.54 0.004 0.29 18.16
Greenhouse- Geisser 0.003 1.51 0.002 4.54 0.035 0.29 6.86
Huynh-Feldt 0.003 1.70 0.002 4.54 0.030 0.29 7.72
Lower- bound 0.003 1 0.003 4.54 0.057 0.29 4.54
Table 12 displays the result from a univariate test for within-subject effects for Right
Triceps max activation. Table 12 indicates there is not a significant difference in maximum
neuromuscular activation for the Right Triceps for within-subjects over the time of the sets, F
(1.70, 18.73) = 3.16, p = .072.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 48
Table 12 Univariate Test for Right Triceps Max Activation
Table 13 displays the result from a univariate test for within-subject effects for the Left
Pectoralis mean activation. Table 13 indicates there is not a significant difference in mean
neuromuscular activation for the Left Pectoralis Major for within-subjects over the time of the
sets, F (4,44) = 1.07, p = .379.
Table 13 Univariate Test for Left Pectoralis Mean Activation
Source Measure Type III Sum
of Squares
df Mean Square
F Sig. Partial Eta
Squared
Noncent. Parameter
Left Pectoralis
Mean Activation
Sphericity Assumed
0 4 9.52 1.077 0.379 0.089 4.31
Greenhouse- Geisser
0 2.49 0 1.077 0.366 0.089 2.683
Huynh-Feldt 0 3.276 0 1.077 0.375 0.089 3.53
Lower- bound
0 1 0 1.077 0.322 0.089 1.077
Source Measure
Type III Sum
of Squares
df Mean Square F Sig. Partial
Eta Squared
Noncent. Parameter
Right Triceps
Max Activation
Sphericity Assumed 0.024 4 0.006 3.16 0.023 0.223 12.64
Greenhouse- Geisser 0.024 1.702 0.014 3.16 0.072 0.223 5.379
Huynh-Feldt 0.024 1.982 0.012 3.16 0.063 0.223 6.263
Lower- bound 0.024 1 0.024 3.16 0.103 0.223 3.16
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 49
Table 14 Univariate Test for Left Pectoralis Maximum Activation
Source Measure
Type III Sum
of Squares
df Mean Square F Sig. Partial
Eta Squared
Noncent. Parameter
Left Pectoralis
Max Activation
Sphericity Assumed 0.019 4 0.005 1.09 0.376 0.09 4.339
Greenhouse- Geisser 0.019 1.82 0.011 1.09 0.351 0.09 1.974
Huynh-Feldt 0.019 2.161 0.009 1.09 0.358 0.09 2.344
Lower- bound 0.019 1 0.019 1.09 0.32 0.09 1.085
Table 14 displays the result from a univariate test for within-subject effects for the Left
Pectoralis max activation. Table 14 indicates there is no significant difference in mean
neuromuscular activation for the Left Pectoralis Major for within-subjects over the time of the
sets, F (4,44) = 1.09, p = .351.
Table 15 Univariate Test for Left Triceps Mean Activation
Source Measure
Type III Sum
of Squares
df Mean Square F Sig. Partial
Eta Squared
Noncent. Parameter
Left Triceps Mean
Activation
Sphericity Assumed 0.003 4 0.001 7.34 0 0.4 29.35
Greenhouse- Geisser 0.003 1.53 0.002 7.34 0.008 0.4 11.19
Huynh-Feldt 0.003 1.72 0.002 7.34 0.006 0.4 12.63
Lower- bound 0.003 1 0.003 7.34 0.02 0.4 7.34
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 50
Table 15 displays the result from a univariate test for within-subject effects for Left
Triceps mean activation. Table 15 indicates there is a significant difference in mean
neuromuscular activation for the Left Triceps for within-subjects over the time of the sets, F
(1.53,20.8) = 7.34, p = .008.
Table 16 Univariate Test for Left Triceps Maximum Activation
Source Measure Type III Sum
of Squares
df Mean Square
F Sig. Partial Eta
Squared
Noncent. Parameter
Left Triceps
Max Activation
Sphericity Assumed
0.005 4 0.001 1.09 0.38 0.09 4.34
Greenhouse- Geisser
0.005 3.28 0.001 1.09 0.37 0.09 3.56
Huynh-Feldt 0.005 4 0.001 1.09 0.38 0.09 4.34
Lower- bound
0.005 1 0.005 1.09 0.32 0.09 1.09
Table 16 displays the result from a univariate test for within-subject effect for Left Triceps max
activation. Table 16 indicates there is not a significant difference in maximum neuromuscular
activation for the Left Triceps for within-subjects over the time of the sets, F (4,44) = 1.09, p =
.38.
Table 17 displays the result from a univariate test for within-subjects effect for RPE.
Table 17 indicates there is a significant difference in Rate of Perceived Exertion for within-
subjects over the time of the sets, F (4,44) = 1.09, p = 0.38.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 51
Table 17 Univariate test for Rate of Perceived Exertion
Source Measure Type III Sum
of Squares
df Mean Square
F Sig. Partial Eta
Squared
Noncent. Parameter
RPE
Sphericity Assumed
10.067 4 2.517 11.615 0.000 0.514 46.462
Greenhouse- Geisser
10.067 2.804 3.591 11.615 0.000 0.514 32.564
Huynh-Feldt 10.067 3.861 2.608 11.615 0.000 0.514 44.841
Lower- bound
10.067 1 10.067 11.615 0.006 0.514 11.615
A post-hoc Pair-Wise Comparison between sets was conducted to determine between
which set there was a significant difference for neuromuscular activation. The data indicated
there was a significant difference in mean neuromuscular activation for Right Triceps between
set 2 and set 5.
Table 18
Pair-Wise Comparison Between Sets
Measure (I) Sets (J) Sets Mean
Difference (I-J)
Std. Error Sig.
b
95% Confidence Interval for Differenceb
Lower Bound
Upper Bound
Right Triceps Mean
Activation
2 5 .013* 0.003 0.025 0.001 0.025
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 52
Table 19
Friedman Test for Differences in RPE between Sets
N 12 Chi-Square 26.500 df 4 Asymp. Sig. .000
The results of the Friedman test suggest there was also a statistically significant
difference in perceived effort depending on the set, χ2 (4) = 726.500, p = 0.000
To examine where the differences actually occur, a separate Wilcoxon signed-rank
tests on the different combinations of related groups. A Bonferroni adjustment was applied to the
results the Wilcoxon tests in order to reduce the likely hood of making a Type 1 error because
multiple comparisons were made. Since 10 comparisons were made, the new level of
significance is 0.05 / 10 = 0.005. Table 20 and table 21 displays the results of the Wilcoxon
signed-rank test.
Table 20
Wilxocon Signed-Rank Test for Differences in RPE Between Sets
T2_RPE - T1_RPE
T3_RPE - T1_RPE
T4_RPE - T1_RPE
T5_RPE - T1_RPE
T3_RPE - T2_RPE
Z -2.121b -2.460b -2.762b -2.739b -1.732b Asymp. Sig. (2-tailed)
.034 .014 .006 .006 .083
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 53
Table 21
Wilxocon Signed-Rank Test for Differences in RPE Between Sets Continued
T4_RPE - T2_RPE
T5_RPE - T2_RPE
T4_RPE - T3_RPE
T5_RPE - T3_RPE
T5_RPE - T4_RPE
Z -2.121b -2.530b -1.342b -1.890b -1.414b
Asymp. Sig. (2-tailed)
.034 .011 .180 .059 .157
There results of the Wilcoxon Signed rank test indicate there were no significant
difference in RPE between sets.
As indicated in figure 1, it was found that the power for the present study was .92, which
satisfied the .8 threshold (Field, 2009)
Figure 1 displays the results for a Post hoc Power Analysis.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 54
CHAPTER 5
DISCUSSION
The purpose of this study is to investigate the effects of 1-minute rest interval on mean
and maximum neuromuscular activation levels (millivolts) in the pectoralis major and triceps
brachii lateral head, and the rate of perceived exertion (RPE) using 40% 1RM during the chest
press exercise. Neuromuscular activation was assessed using surface EMG and RPE was
assessed using the Modified Borg 10 Scale.
There were two hypotheses for the present study. The first hypothesis stated that a 1-
minute rest interval at 40% 1RM on the chest press will have a significant effect on
neuromuscular activation in the pectoralis major and triceps brachii lateral head, as measured by
electromyography (EMG). Maximum and mean EMG for each muscles was recorded for each
of the 5 sets. The second hypothesis stated that a 1-minute rest interval at 40% 1RM on the chest
press will have a significant effect on exertion as assessed by the Rating of Perceived Exertion
(RPE) scale, which was assessed after the completion of each of the 5 sets.
The data collected from the present study was analyzed by utilizing a repeated-measures
ANOVA test which showed that 1-minute rest interval caused a significantly lower mean
neuromuscular activity in the right triceps between sets 2 and 5, p =.003. However, there was no
significant differences found in mean or maximum neuromuscular activation levels between the
5 sets in either the left pectoralis major, right pectoralis major, or left triceps (p >.05). In
addition, there was no significant difference in RPE between any of the 5 sets. Furthermore, this
chapter compares the results observed during the experimental protocol to the originally
predicted hypothesis, and previous research conducted.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 55
Although overall there were no significant differences in neuromuscular activity between
the 5 sets, the results of this study are important because they further build on a previous research
by Davó and colleagues, (2015) who found that performing 5 sets of the bench press exercise at
40% 1RM with a 1-minute rest interval caused a decrease in mean and peak power output, an
increase in blood lactate concentrations, rate perceived exertion, and greater DOMS compared to
the 2-minute and 3-minute rest interval. One major limitation their study was they did not assess
neuromuscular information. The results from the present study suggests that the observed
decreases in mean and peak power output may not be related to neurological factors (such as
neural fatigue), but may be more the results of metabolic factors, such as the observed increase in
lactate concentrations.
The findings in the present study and the one performed by Davó and colleagues (2015)
is consistent with our current understanding of muscle physiology and response to exercise.
When a muscle is engaged, it will generate metabolites, such as hydrogen and phosphate, which
may reduce the force per cross-bride, reduce the force generated per given calcium
concentration, and inhibit the release of calcium by the sarcoplasmic reticulum (Powers &
Howley, 2018). Davó and colleagues (2015) observed this increase in lactate concentration and
hydrogen ions, which can explain the reduction in mean and peak power output. Thus, the
decrease in power observed by by Davó and colleagues (2016) may have been more likely due to
the accumulation of metabolic factors than peripheral neuromuscular fatigue factors, which is
suggested by the lack of overall significant changes in mean and maximum neuromuscular
activation as shown in the present study. Peripheral neuronal fatigue can be caused by the
sarcolemma being repeatedly stimulated, which reduces the size and frequency of the action
potentials or a block within the t-tubule, resulting in less calcium being released in the
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 56
sarcoplasmic reticulum (Powers & Howley, 2018). It has been shown that when the body is
unable to fully recover from exercise and metabolites such as hydrogen and phosphate can reach
levels that in turn, reduce motor unit recruitment, resulting in fatigue, (BuckThorpe et al. 2015).
The reduction in recruited motor units may result in neural fatigue, which is defined as an
induced reduction in the ability to produce force or power with a muscle or muscle group.
Ultimately, the production of force or power depends on contractile mechanisms within skeletal
muscle fibers (Taylor et al. 2016). A decrease in motor unit recruitment was not observed in the
present study since the neuromuscular activity was not significantly different. Thus, suggesting
neuromuscular fatigue could have been attributed to metabolite accumulation.
The lack of significant findings during the present study may be due to that 40% of 1RM
with a 1-minute rest interval may not have been intense enough to elicit neural fatigue, which
may be supported by Schoenfeld et al., 2014., who used EMG and demonstrated that performing
a leg press exercise at 30% of one’s 1-RM was not sufficient to effectively activate or engage
full motor recruitment, when compared to a load of 75% 1RM. Further, a study conducted by
Schoenfeld et al., 2016., showed that the participants were able to complete more repetitions at
50%1RM and had similar EMG peaks as 80%1RM. Despite the similar EMG peaks, they were
significantly greater at 80%1RM compared to 50%1RM (2016). Although, the work load at
50%1RM were able to produce equal EMG peaks during the study, it still suggests that using
lighter load is sufficient stress to cause increase EMG activation within the anterior deltoid,
triceps brachii, and pectoralis major.
Similarly, Jenkins et al. 2015, found that muscle activation and EMG amplitudes were
significantly greater in participants during the 80% 1RM than 30%RM. This suggests that using
relatively light weight, such as 30% or 40% of the participants’ 1RM may not elicit enough of a
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 57
metabolic response that in turn may cause neural fatigue. Furthermore, in a study conducted by
Pinto et al. 2013, investigated the relationship between strength and electromyography signal on
bench press. They found significant difference in neuromuscular activation levels in pectoralis
major, anterior deltoid and posterior deltoid between the intensities of 60 and 70% of the
maximal voluntary contraction, as well as between 70 and 80% (P < 0.05), he suggested that
loads greater than 60% 1RM during resistance training may be sufficient to cause significant
changes in neuromuscular activity within the pectorals major, anterior deltoid and posterior
deltoid will continue to occur until the loads reach near maximal intensity.
Research utilizing 40% 1RM for resistance training to increase muscular performance
and neuromuscular activation is conflicting. Research suggest that working with loads
corresponding to 30%1RM and 40%1RM are not sufficient stressors to elicit significant changes
in neuromuscular activation levels (Jenkins et al. 2015: Davó et. al, 2015). Moreover, using loads
as light as 50% 1RM appear to provide sufficient stress to cause increase neuromuscular
activation and using loads of 60% 1RM, 70% 1RM, and 80%1RM continue to increase neural
recruitment until working with loads near maximum effort, and will have no significant
difference in neuromuscular activation (Pinto et al. 2013; Schoenfeld et al., 2014; Schoenfeld et
al., 2016). Thus, future research may investigate neuromuscular activity during a 1-minute rest
interval at 50-80% 1RM over several sets and determine if this relates to changes in power
during a bench press exercise.
There were several factors that may have affected the study outcomes. First, the
participant’s hand placement on the bench press bar was not standardized. This is a noteworthy
limitation because Ji et. al. 2016 examined the effects of varying grips widths and muscle
activation levels on the bench press. They found as grip width shorten neuromuscular activity of
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 58
the pectoralis major decreased. In addition, when the grip width was equal to shoulder width, the
neuromuscular activity of pectoralis minor is lowest. Moreover, when the grip width is smaller or
larger than the shoulder width, the neuromuscular activity is higher. As the grip distance
increases, the neuromuscular activity of posterior deltoid muscle and triceps increases. Similarly,
Calatayud et al. 2018 results showed an increased neuromuscular activity in pectoralis major at
wider grip widths and an increase in triceps brachii activity at narrower grip widths. Therefore,
standardizing grip width may limit variability in neuromuscular activation of the muscles being
investigated.
Another factor that may have affected the outcome of the present study was the warm up.
During the present study a dynamic whole body warm up was performed for 10 minutes prior to
the bench press exercise. The warm up was indicated to increase the body temperate, warm up
and activate the muscle that were being targeted, pectoralis major, and lateral head of the triceps
brachii. Mccrary and colleagues (2015) showed that upper body dynamic warms up enhanced
muscle endurance and muscle performance. So in future studies a dynamic warm up that targets
specific muscle being utilized in an exercise show be the main focus of the warm up. For
example. If a person is performing a bench press, then a warm up focusing on the prime movers
should be targeted to prepare the muscles prior to the exercise.
In conclusion, the main results of this study indicated that utilizing 1-minute rest interval
is sufficient to cause a significantly lower mean neuromuscular activation in the right triceps
between sets 2 and 5, p =.003. However, there was no significant differences found in mean or
maximum neuromuscular activation levels between the 5 sets in either the left pectoralis major,
right pectoralis major, or left triceps (p >.05). In addition, there was no significant difference in
RPE between any of the 5 sets. The results of the present study add to the body of research
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 59
suggesting that the observed decreases in mean and peak power output may not be related to
neurological factors (such as neural fatigue), but may be more the results of metabolic factors,
such as the observed increase in lactate concentrations (Davo et al.2015).
Future studies could further exam neuromuscular activity during a 1-minute rest interval
at higher loads such as 60% 1-RM, or 80% 1- RM. Also, further research is warranted to
investigate the effects on neuromuscular activity at varying rest intervals (2-minutes and 3-
minutes) at lighter loads (40% 1-RM) and higher loads (60% 1-RM, 80% 1- RM)
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 60
References
1. ACSM. (2014) American College of Sports Medicine. ACSM's Guidelines for Exercise
Testing and Prescription. Medicine Science in Sports and Exercise. 9th ed
2. Allen, D. G., Lamb, G. D., & Westerblad, H. (2008). Skeletal Muscle Fatigue: Cellular
Mechanisms. Physiological Reviews,88(1), 287-332.
doi:10.1152/physrev.00015.2007.
3. Arazi, A., & Asadi, A. (2011). Effects of 8 Weeks Equal-Volume Resistance Training
with Different Workout Frequency on Maximal Strength, Endurance and Body
Composition. International Journal of Sports Science and Engineering, 5 (2011)
2, pp 112-118
4. Baker, D., & Newton, R. U. (2005). Acute Effect On Power Output Of Alternating An
Agonist And Antagonist Muscle Exercise During Complex Training. Journal of
Strength and Conditioning Research,19(1), 202-205. doi:10.1519/00124278-
200502000-00034
5. Beachle, T., R., Earle, R.W., 2008.Essentials of Strenght Training and Conditioning.
Champaign (IL). Human Kinetics.
6. Broosk. G.A., Faheu, T.D., Baldwin, K.M. (1995). Exercise Physiology: Human
Bioenergetics and Its Applications (4th ed.) McGraw Hill. New York, NJ.
7. Buckthorpe, M., Pain, M. T., & Folland, J. P. (2014). Central fatigue contributes to the
greater reductions in explosive than maximal strength with high-intensity
fatigue. Experimental Physiology,99(7), 964-973.
doi:10.1113/expphysiol.2013.075614.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 61
8. Campbell, B. M., Kutz, M. R., Morgan, A. L., Fullenkamp, A. M., & Ballenger, R.
(2014). An Evaluation of Upper-Body Muscle Activation During Coupled and
Uncoupled Instability Resistance Training. Journal of Strength and Conditioning
Research,28(7), 1833-1838. doi:10.1519/jsc.0000000000000350.
9. Calatayud, J., Vinstrup, J., Jakobsen, M. D., Sundstrup, E., Colado, J. C., & Andersen, L.
L. (2017). Attentional Focus and Grip Width Influences on Bench Press
Resistance Training. Perceptual and Motor Skills,125(2), 265-277.
doi:10.1177/0031512517747773.
10. Daniels, R. J., & Cook, S. B. (2017). Effect of instructions on EMG during the bench
press in trained and untrained males. Human Movement Science,55, 182-
188.doi:10.1016/j.humov.2017.08.010
11. Davó, J. L., Solana, R. S., Marín, J. M., Fernández, J. F., & Ramón, M. M. (2016). Rest
Interval Required for Power Training with Power Load in the Bench Press Throw
Exercise. Journal of Strength and Conditioning Research, 30(5), 1265-1274.
doi:10.1519/jsc.0000000000001214.
12. Eklund, D., Pulverenti, T., Bankers, S., Avela, J., Newton, R., Schuman, M., Hakkinen,
K. 2015. Neuromuscular Adaptation to Different Modes of Combined Strength
and Endurance Training. International Journal of Sports Medicine.36:120-129.
13. Fahs, C. A., Loenneke, J. P., Thiebaud, R. S., Rossow, L. M., Kim, D., Abe, T., Bemben,
M. G. (2014). Muscular adaptations to fatiguing exercise with and without
blood flow restriction. Clinical Physiology and Functional Imaging,35(3), 167-
176. doi:10.1111/cpf.12141
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 62
14. Fink, J.E., Schoenfeld, B.J., Nakazato, K. (2016). Acute and Long-term Responses to
Different Rest Intervals in Low-load Resistance Training. International Journal of
Sports Medicine. 1- 8. DOI: 10.1055/s-0042-119204.
15. Folland, J. P., & Williams, A. G. (2007). The Adaptations to Strength Training. Sports
Medicine,37(2), 145-168. doi:10.2165/00007256-200737020-00004
16. Freitas, M., Paz, G.A., Miranda, H., Lima, V., Bentes, C.M., Novas, J., Vigario, P.,
Willardson, .M. (2015) Maximal Repetition Performance, Rating of Perceived
Exertion and Muscle Fatigue During Paired Set Training Performed With
Different Rest Intervals. Journal of Exercise Science & Fitness.13: 104-110.
17. Golas, A., Maszczyk, A., Stastny, P., Wilk, M., Ficek, K., Lockie, R., & Zajac, A. (2018).
A New Approach to EMG Analysis of Closed-Circuit Movements Such as the
Flat Bench Press. Sports,6(2), 27. doi:10.3390/sports6020027.
18. Green, C. M., & Comfort, P. (2007). The Effect of Grip Width on Bench Press
Performance and Risk of Injury. Strength and Conditioning Journal,29(5), 10-14.
doi:10.1519/00126548-200710000-00001.
19. Gentil, P., Fisher, A.S., Martorelli, R.M., Lima, M.B. (2014). Effects of equal-volume
resistance training performed one or two times a week in upper body muscle size
and strength of untrained young men. Journal of Sports Medicine and Physical
Fitness, 55(3).
20. Gentil, P., Fisher, J., Steele, J., & Arruda, A. (2017). Dose-Response of 1, 3, and 5 Sets
of Resistance Exercise on Strength, Local Muscular Endurance, and
Hypertrophy. Journal of Strength and Conditioning Research,31(1).
doi:10.1519/jsc.0000000000001231
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 63
21. Grgic, J., Schoenfeld, B. J., Skrepnik, M., Davies, T. B., & Mikulic, P. (2017). Effects of
Rest Interval Duration in Resistance Training on Measures of Muscular Strength:
A Systematic Review. Sports Medicine,48(1), 137-151. doi:10.1007/s40279-017-
0788-x
22. Haff, G., & Dumke, C. (2012). Laboratory manual for exercise physiology. Champaign,
IL: Human Kinetics. 90 – 112.
23. Jenkins, N. D., Housh, T. J., Buckner, S. L., Bergstrom, H. C., Cochrane, K. C., Hill, E.
C., Cramer, J. T. (2016). Neuromuscular Adaptations After 2 and 4 Weeks of
80% Versus 30% 1 Repetition Maximum Resistance Training to Failure. Journal
of Strength and Conditioning Research,30(8), 2174-2185.
doi:10.1519/jsc.0000000000001308
24. Ji, Z., Wang, H., Jiang, G., & Li, L. (2016). Analysis of Muscle Activity Utilizing Bench
Presses in the AnyBody Simulation Modelling System. Modelling and Simulation
in Engineering,2016, 1-7. doi:10.1155/2016/3649478.
25. Kompf, J., & Arandjelović, O. (2016). The Sticking Point in the Bench Press, the Squat,
and the Deadlift: Similarities and Differences, and Their Significance for
Research and Practice. Sports Medicine,47(4), 631-640. doi:10.1007/s40279-016-
0615-9.
26. Lagally, K. M., Mccaw, S. T., Young, G. T., Medema, H. C., & Thomas, D. Q. (2004).
Ratings Of Perceived Exertion And Muscle Activity During The Bench Press
Exercise In Recreational And Novice Lifters. Journal of Strength and
Conditioning Research,18(2), 359-364. doi:10.1519/00124278-200405000-00028.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 64
27. Lee, Y., Lim, B.O., (2017). Effects of grip width and hand orientation on muscle
activities of upper body during the Lat pull-down. Korean Journal of Sport
Science,28(3), 556-565.doi:10.24985/kjss.2017.28.3.556.
28. Looney, D. P., Kraemer, W. J., Joseph, M. F., Comstock, B. A., Denegar, C. R.,
Flanagan, S. D., Maresh, C. M. (2016). Electromyographical and Perceptual
Responses to Different Resistance Intensities in a Squat Protocol. Journal of
Strength and Conditioning Research,30(3), 792-799.
doi:10.1519/jsc.0000000000001109
29. Maia, M. D., Paz, G. A., Miranda, H., Lima, V., Bentes, C. M., Novaes, J. D.,
Willardson, J. M. (2015). Maximal repetition performance, rating of perceived
exertion, and muscle fatigue during paired set training performed with different
rest intervals. Journal of Exercise Science & Fitness,13(2), 104-110. doi:
10.1016/j.jesf.2015.08.002.
30. Mangine, G. T., Hoffman, J. R., Gonzalez, A. M., Townsend, J. R., Wells, A. J., Jajtner,
A. R.,Stout, J. R. (2015). The effect of training volume and intensity on
improvements in muscular strength and size in resistance-trained
men. Physiological Reports,3(8). doi:10.14814/phy2.12472
31. Marshall, P.W.M., Robbins, D.A., Wrightson, A.W., Siegler, J.C. (20120. Acute
Neuromuscular and Fatigue Responses to the Rest-Pause Method. Journal of
Science and Medicine in Sport. 15: 153-158.
32. Martorelli, A., Bottaro, M., Vierira, A., Rocha-Junior, V., Cadore, E., Prestes, J., Wagner,
D., Martorelli, Saulo. (2015). Neuromuscular and Blood Lactate Responses to
Squat Power Training with Different Rest Intervals between Sets. Journal of
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 65
Sports Science and Medicine.14, 269-275.
33. Mccrary, J. M., Ackermann, B. J., & Halaki, M. (2015). A systematic review of the
effects of upper body warm-up on performance and injury. British Journal of
Sports Medicine,49(14), 935-942. doi:10.1136/bjsports-2014-094228.
34. Ochi, E., Maruo, M., Tsuchiya, Y., Ishii, N., Miura, K., & Sasaki, K. (2018). Higher
Training Frequency Is Important for Gaining Muscular Strength Under Volume-
Matched Training. Frontiers in Physiology,9. doi:10.3389/fphys.2018.00744
35. Penzer, F., Cabrol, A., Baudry, S., & Duchateau, J. (2016). Comparison of Muscle
Activity and Tissue Oxygenation During Strength Training Protocols that Differ
by Their Organization, Rest Intervals Between Sets, and Volume. European
Journal of Applied Physiology, 11(9), 1795-1806.Doi:10.1007/s00421-016-3433-
8.
36. Perceived Exertion (Borg Rating of Perceived Exertion Scale). (2015, August 11).
Retrieved October 08, 2017, from
https://www.cdc.gov/physicalactivity/basics/measuring/exertion.htm
37. Pinto, R., Cadore, E., Correa, C., Silva, B. G., Alberton, C., Lima, C., & Moraes, A. D.
(2013). Relationship Between Workload And Neuromuscular Activity In The
Bench Press Exercise. Medicina Sportiva,17(1), 1-6.
doi:10.5604/17342260.1041876.
38. Powers, S. K., Howley, E.T. (2018). Exercise Physiology: Theory and application to
FIntess and Performance (10th ed.). McGraw Hill. New York, NY
39. Sarabia, J. M., Moya-Ramón, M., Hernández-Davó, J. L., Fernandez-Fernandez, J., &
Sabido, R. (2017). The effects of training with loads that maximise power output
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 66
and individualised repetitions vs. traditional power training. Plos One,12(10). doi:
10.1371/journal.pone.0186601
40. Ratamess, N. A., Chiarello, C.M., Sacco, A. J., Hoffman, J.R., Faigenbaum, A. D., Ross,
R. E., Kang, J. (2012). The Effects of Rest Interval Length Manipulation of the
First Upper-Body Resistance Exercise in Sequence on Acute Performance of
Subsequent Exercise in Men and Women. Journal of Strength and Conditioning
Research, 26(11),2929-2938. doi: 10.1519/jsc.0b013e318270cf0.
41. Robbins, D. W., Young, W. B., Behm, D. G., & Payne, W. R. (2009). Effects of agonist–
antagonist complex resistance training on upper body strength and power
development. Journal of Sports Sciences,27(14), 1617-1625.
doi:10.1080/02640410903365677
42. Saeterbakken, A. H., Mo, D., Scott, S., & Andersen, V. (2017). The Effects of Bench
Press Variations in Competitive Athletes on Muscle Activity and
Performance. Journal of Human Kinetics,57(1), 61-71. doi:10.1515/hukin-2017-
0047.
43. Saeterbakken, A. H., Mo, D., Scott, S., & Andersen, V. (2017). The Effects of Bench
Press Variations in Competitive Athletes on Muscle Activity and
Performance. Journal of Human Kinetics,57(1), 61-71. doi:10.1515/hukin-2017-
0047.
44. Sajad, M., Arsalan, D., Rahmat, A. (2014). Effects of Short Rest Periods on
Neuromuscular Responses to Resistance Exercise in Trained Men. Journal of
Romanian Sports Medicine. vol. X, no 1, 2287-2291.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 67
45. Sánchez-Medina, L., & González-Badillo, J. J. (2011). Velocity Loss as an Indicator of
Neuromuscular Fatigue during Resistance Training. Medicine & Science in Sports
& Exercise,43(9), 1725-1734. doi:10.1249/mss.0b013e318213f880
46. Schoenfeld, B. J., Ratamess, N. A., Peterson, M. D., Contreras, B., Sonmez, G. T., &
Alvar, B. A. (2014). Effects of Different Volume-Equated Resistance Training
Loading Strategies on Muscular Adaptations in Well-Trained Men. Journal of
Strength and Conditioning Research,28(10), 2909-2918.
doi:10.1519/jsc.0000000000000480.
47. Schoenfeld, B. J., Ratamess, N. A., Peterson, M. D., Contreras, B., & Tiryaki-Sonmez, G.
(2015). Influence of Resistance Training Frequency on Muscular Adaptations in
Well-Trained Men. Journal of Strength and Conditioning Research,29(7), 1821-
1829. doi:10.1519/jsc.0000000000000970
48. Schoenfeld, B. J., Peterson, M. D., Ogborn, D., Contreras, B., & Sonmez, G. T. (2015).
Effects of Low- vs. High-Load Resistance Training on Muscle Strength and
Hypertrophy in Well-Trained Men. Journal of Strength and Conditioning
Research,29(10), 2954-2963. doi:10.1519/jsc.0000000000000958
49. Schoenfeld, B. J., Contreras, B., Vigotsky, A. D., Ogborn, D., Fontana, F., & Tiryaki-
Sonmez, G. (2016). Upper body muscle activation during low-versus high-load
resistance exercise in the bench press. Isokinetics and Exercise Science,24(3),
217-224. doi:10.3233/ies-160620
50. Schoenfeld, B. J., Ogborn, D., & Krieger, J. W. (2016). Effects of Resistance Training
Frequency on Measures of Muscle Hypertrophy: A Systematic Review and Meta-
Analysis. Sports Medicine,46(11), 1689-1697. doi:10.1007/s40279-016-0543-8
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 68
51. Scudese, E., Willardson, J. M., Simão, R., Senna, G., Salles, B. F., & Miranda, H. (2015).
The Effect of Rest Interval Length on Repetition Consistency and Perceived
Exertion During Near Maximal Loaded Bench Press Sets. Journal of Strength and
Conditioning Research,29(11), 3079-3083. doi:10.1097/jsc.0000000000000214.
52. Soares,E.G., Brown, L, E,. Gomes, W, A., Correa, D, A., Serpa, E, P., Jarbas Da Silva, J,
Vilela, G, G., Fioravanti, G, V., Aoki, M, S., Lopes, C, R., Marchetti, P, H.
(2016). Comparison between Pre-Exhaustion and Traditional Exercise Order on
Muscle Activation and Performance in Trained Men. Journal of Sports Science
and Medicine 15, 111-117
53. Stastny, P., Golas, A., Blazek, Maszczyk, A., Wilk, M., Pietraszewski, P., Petr, M., Uhlir,
P., Zajac, A. (2017). A Systematic Review of Surface Electromyography
Analyses of the Bench Press Movement Task. PLoS ONE 12(2): e0171632. doi:
10.1371/journal.pone.0171632.
54. Suchomel, T. J., Nimphius, S., & Stone, M. H. (2016). The Importance of Muscular
Strength in Athletic Performance. Sports Medicine,46(10), 1419-1449.
doi:10.1007/s40279-016-0486-0.
55. Taylor, J. L., Amann, M., Duchateau, J., Meeusen, R., & Rice, C. L. (2016). Neural
Contributions to Muscle Fatigue. Medicine & Science in Sports &
Exercise,48(11), 2294-2306. doi:10.1249/mss.0000000000000923
56. Tibana, R.A., Prestes, J., Nsacimento, D.D.A., Martins, O.V., Desanta, F.S., Balsamo, S.
(2011). Higher Muscular Performance in Adolesent Compared with Adults After
Resistance Training Sessions with Different Rest Intervals. Journal of Strength
and Conditioning Research. 0(0). 1-6.
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 69
57. Tibana, R.A., Vieira, D.C.L., Tarja, V. (2013). Effects of Rest Interval Length on Smith
Machine Bench Press Performance and Perceived Exertion in Trained Men.
Perceptual & Motor Skills: Exercise & Sport. 117, 3, 682-695. DOI
10.2466/60.30.PMS.117x27z2.
58. Tillaar, R. V., & Saeterbakken, A. H. (2013). Fatigue effects upon sticking region and
electromyography in a six-repetition maximum bench press. Journal of Sports
Sciences,31(16), 1823-1830. doi:10.1080/02640414.2013.803593.
59. Tillaar, R. V., & Saeterbakken, A. (2014). Effect of Fatigue Upon Performance and
Electromyographic Activity in 6-RM Bench Press. Journal of Human
Kinetics,40(1), 57-65. doi:10.2478/hukin-2014-0007
60. Tufano, J.J., Conlon, J.A., Nimphius, S., Brown, L.E., Seitz, L.B., Williamson, B.D.,
Half, G.G. (2016). Maintenance of Velocity and Power with Cluster Sets
During High-Volume Back Squats. International Journal of Sports Physiology
and Performance, 2016, 11, 885- 892 http://dx.doi.org/10.1123/ijspp.2015-0602
61. Vorup, J., Tybirk, J., Gunnarsson, T. P., Ravnholt, T., Dalsgaard, S., & Bangsbo,J.
(2016). Effect of speed endurance and strength training on performance, running
economy and muscular adaptations in endurance-trained runners. European
Journal of Applied Physiology,116(7),1331-1341.doi:10.1007/s00421-016-3356-
4.
62. Wan, J., Qin, Z., Wang, P., Sun, Y., & Liu, X. (2017). Muscle fatigue: General
understanding and treatment. Experimental & Molecular Medicine,49(10).
doi:10.1038/emm.2017.194
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 70
63. Weakley, J. J., Till, K., Read, D. B., Roe, G. A., Darrall-Jones, J., Phibbs, P. J., & Jones,
B. (2017). The effects of traditional, superset, and tri-set resistance training
structures on perceived intensity and physiological responses. European Journal
of Applied Physiology,117(9), 1877-1889. doi:10.1007/s00421-017-3680-3
EFFECTS OF REST INTERVALS ON NEUROMUSCULAR ACTIVITY 71
Participant Recruitment Flyer
WANTED: Participants for the study on the Effects of Rest Intervals on Neuromuscular Activity • The study will examine 1-minute rest interval and the effects on neuromuscular activity
of the pectoralis major and triceps, rate of perceived exertion and fatigue during the
bench press exercise.
• The study will last 1 week and consist of 2 sessions lasting 20 – 30 minutes.
• To be eligible the participant has to be a male that engages in regular physical activity,
quantified as at least 150 minutes of moderate physical activity for past 3 months, and is
between 18 - 30 years of age. The 150 minutes of physical activity will consist of a
combination of aerobic and resistance exercises.
• Help us determine the optimal rest interval duration to elicit the most neuromuscular
activity during the chest press to improve performance.
• Participation is voluntary and confidential
• All participants will be required to complete sessions in Kean University’s Exercise
Physiology Laboratory (D172) in the D’Angola building
• This study is part of fulfillment for my Master’s Degree in Exercise Science program at
Kean University.
Please contact Richard Osolinski at (732) 570-3962 or [email protected] or Co-Investigator Dr. Timothy Marshall at (908) 737-6177 or [email protected] for more information or to participate. Faculty Advisor: Dr. Walter Andzel Contact: (908) 737-0662 or [email protected] Institutional Review Board Acting Director: Dr. Jessica Adams
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INFORMED CONSENT Title of Project: The Effects of Rest Interval on Neuromuscular Activity Primary Investigator: Richard Osolinski Department: Physical Education, Recreation, and Health Contact Information: Telephone (732) 570 3962, E: [email protected] Co-Investigator: Dr. Timothy Marshall PhD., M.S., ACSM/ACS-CET Department: School of Physical Therapy, DPT Program at Kean University Contact information: (908) 737- 6177, E: [email protected] Faculty Advisor: Dr. Walter Andzel Department: Physical Education, Recreation, and Health Contact Information: Telephone (908) 737 0662, E: [email protected] Invitation to Participate: You are being invited to take part in a research study conducted by Richard Osolinski, a graduate student at Kean University in Union, NJ. By participating you will help to learn about the effects of rest interval duration on neuromuscular activity, rate of perceived exertion and fatigue. This study will aim to investigate and determine the effects of 1-minute rest interval on neuromuscular activity of the pectoralis major and triceps, perceived exertion, and fatigue while performing chest press exercise. Participant Selection: You have been invited to participate in this study because you are a male that engages in regular physical activity, quantified as at least 150 minutes of moderate physical activity for past 3 months, and is between 18 - 30 years of age. The 150 minutes of physical activity will consist of a combination of aerobic and resistance exercises. Purpose of Study: The purpose of this study is to investigate the effects of 1-minute rest interval on neuromuscular activation, rates of perceived exertion and fatigue during the chest press exercise. Maximizing neuromuscular activation will improve the communication between the nervous system and musculoskeletal system by increasing motor unit recruit as well as increasing neural firing patterns. Improving the interaction between nervous system and musculoskeletal system in turn will maximize athletic performance. Procedures: If you agree to take part in this study, the experiment will take place at Kean University in the
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Exercise Physiology Laboratory (D172) in the D’Angola building, located on the main campus. You will meet with the primary investigator on an individual basis and will consist of 2 meetings lasting approximately 20 – 30 minutes each. The meetings will be conducted in private and will be scheduled 48 hours apart.
The first meeting, you will complete an informed consent form, and a Physical Activity Readiness Questionnaire (PAR-Q) to determine if the you are qualified to exercise. In addition, the primary investigator will collect and record baseline measurements such as height, weight, and body mass index. The weight, percent body fat, and body mass index will be assessed by using a Bioelectrical impedance analysis (BIA) Tanita TBF-410GS Body Composition Analyzer Scale, and height measured using a Detecto 439 mechanical doctor scale. After the baseline measurements are obtained, you will be tested for your one repetition maximum test, and will be familiarized with all equipment, training, and the experimental protocol.
Prior to assessing muscular strength, a 5-minute dynamic warmup will be performed and additional 5 minutes spent on a Life Fitness 9500HR treadmill at a walking speed of 2.5 – 3.0 mph. The additional experimental session will consist of a strength training protocol which includes 5 sets of 8 repetitions, using 40% of 1RM for the bench press exercise, but experiencing a 1-minute rest. The variables investigated during this study are level of neuromuscular activity, rating of perceived exertion (RPE), and fatigue. For each set, the mean and maximum neuromuscular activity of the left and right pectoralis major and triceps will be assessed using surface EMG and exertion will be assessed using Rating of Perceived Exertion (RPE). To limit experimental variability, the same qualified primary investigator and co-investigator will conduct and supervise all testing sessions.
Participation: Participation in this research study is completely voluntary and has no effect on your standing at Kean University. If you agree to be in the study, but change your mind at any period, and for any reason, you may withdraw at any time without penalty or loss of benefits. Discomforts and Potential Risks: This study involves moderate risk for muscle strain and moderate risk for dropping the barbell on ones’ chest. A dynamic warm-up (5-10 minutes) will be conducted prior to testing. The proper form and technique for the exercise performed will be encouraged through proper demonstration and verbal instructions given by the primary investigator. All testing will be performed individually to allow full supervision at all times during the study. Discomfort may be felt with one repetition maximum bench press and dynamic warms. Also, in order to apply the EMG electrode, it must be applied with an adhesive strip which may cause slight discomfort during the removal such as removing a band aid. Furthermore, it is possible you may feel bothered about your performance during the bench press test and regarding your body mass calculations. If the participant has excessive discomfort or pain during the exercise, it must be reported to the primary investigator or co-investigator immediately. Potential Benefits: The potential benefits associated with the participation in this study are as follows: you will gain personal awareness of weight, height, body mass index, and one repetition max for the bench press. The investigator will educate and teach you proper techniques essential for resistance
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training. The information gathered from this study can be valuable for coaches, trainers, and clinicians who wish to develop strength and conditioning protocols or rehabilitative programs to optimize athletic performance. Financial Obligation: There is no financial obligation to you associated with your participation in this study. Compensation/Treatment: There is no compensation associated with participating in this study. In the event of an injury as a result in participating in this study, the primary investigator or co- investigator will contact Heath Services at (908) 737-4880 or [email protected], or the campus security emergency number at (908) 737-4800. Campus security will take the appropriate action and dispatch personnel to the location as well as call the Health Center or 911 if necessary. If needed, psychological counselling is available through the Counseling and Disability Services office, and can be reached at (908) 737-4850, or [email protected]. The primary investigator who is Basic Life Support (BLS), Automated External Defibrillator (AED,) and Advanced Cardiovascular Life Support (ACLS) certified, and co-investigator which has a Doctoral degree in Heath Science, Master degree in Exercise Science and Certified Cancer Exercise Trainer will be present at all times to supervise and ensure participants’ safety. Confidentiality: Your participation in this study is confidential. All measurements and test results will be kept in a locked cabinet at Kean University Exercise Physiology Laboratory, and only the primary investigator, co-investigator, faculty advisor, and the IRB will have access to your data. Names will not be attached to any of the results, and all records will be shredded or deleted 5 years after the completion of the study. Questions/Comments: If you have any questions or comments about this study, I can answer them now. If you have any questions about your rights as a research participant or any questions, you can contact the primary investigator Richard Osolinski, co-investigator Dr. Timothy Marshall or Dr. Walter Andzel, or the Kean University Institutional Review Board. Primary investigator/Graduate student: Richard Osolinski (732) 570 3962, E: [email protected]. Co-Investigator: Dr. Timothy Marshall PhD., M.S., ACSM/ACS-CET (908) 737-6177, E: [email protected] Faculty Advisor: Dr. Andzel (908) 737-0662 , E: [email protected]. IRB: (908) 737-3461 or [email protected].
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Agreement to Participate: Please sign and print your name as designated below if you agree to participant in this study, “The Effects Rest Interval on Neuromuscular Activity.” By signing this form, you are indicating that you have read and understood the information in this document and agree to participate in this study. If at any time you have questions or concerns regarding this study, please do not hesitate to contact the primary investigator or the faculty advisor at the telephone or email addresses provided in this document. Signature of Participant Date Printed Name of Participant Date Signature of Primary Investigator Date Signature of Faculty Advisor Date
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Participant Debriefing Form I would like to express my gratitude for volunteering to participate in this research study. The purpose of this study was to investigate the effects of 1-minute rest interval on neuromuscular activation, the rate of perceived exertion (RPE), and fatigue during the chest press exercise. For each set, the mean and maximum neuromuscular activity of the left and right pectoralis major and triceps was assessed using surface EMG and exertion was assessed using Rating of Perceived Exertion (RPE) The study consisted of 2 experimental sessions. During, the first meeting the proper documents were completed, baseline measurements of height, weight, and body mass index of participants were obtained and recorded. In addition, one repetition maximum (1RM) was determined and participants were familiarized with all equipment, training and testing procedures. The second session consisted of a strength training protocol which included 5 sets of 8 repetitions, using 40% of 1RM for the bench-press exercise, but subjected to a 1-minute rest interval. All personal information was recorded and secured to protect your confidentiality. Your name was not used and only the investigators and IRB had access to your personal information and results of the study. All records and documents were locked in the Exercise Physiologist Laboratory at Kean University in Union, NJ, and will be destroyed five years after the publication of the study. Your participation in this study was completely voluntary. At any point throughout the duration of this study you may have withdrawn with no negative repercussions. By reading and signing the consent form you agreed that you understood the purpose, risks, and benefits of this study. If you have any further questions or concerns, you may contact the primary investigator, Richard Osolinski at (732) 570-3962 or [email protected] or Co-Investigator Dr. Timothy Marshall PhD., M.S., ASCM/ACS-CET at (908) 737- 6177 or [email protected], or the faculty advisor, Dr. Walter Andzel (908) 737-0662 or [email protected]. If you have any questions about your right as a research participant, please contact the Institutional Review Board, Office of Research and Sponsored Programs, Kean University at (908) 737-3461 or [email protected]. If needed, psychological counseling is available through the Counseling and Disability Services, and may be reached at (908) 737-4850, or counseling @kean.edu. I greatly appreciate your participation. Signature of researcher _________________________________________
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RPE Modified Borg 0 – 10 Scale
0 At rest
1 Very easy
2 Somewhat easy
3 Moderate
4 Somewhat hard
5 Hard
6
7 Really Hard
8
9 Really, really hard
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