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Journal Article Review
Background (Section 1: Reason for article choice AND Importance)
This paper will review the journal article “Critical Power: An important fatigue
threshold in exercise physiology” (Poole et al., 2016). This article is published by the American
College of Sports Medicine, in the Journal of Medicine and Science in Sport and Exercise. This
article was chosen due to how interesting the concept of fatigue threshold is to the writer. The
writer of this paper has an interest in how fatigue threshold works in both sports but also on the
general ability of an individual to perform exercises. There are several ways in which this article
has an importance to exercise physiology, namely in discussing the components of critical
power, VO2 max, workout intensity, and how that is all interrelated to an individual’s fatigue
threshold. Poole et al. (2016) provided a discussion on how critical power is integrated in various
physiological processes in the body, including metabolic, respiratory, and contractile, giving
both scientific and practical ways in which to utilize the their framework.
There is a natural interes among those who study human physiology and sports in how
fatigue develops in an individual and how that is linked to their performance of exercises (Poole
et al., 2016). When an individual engages in high intensity exercises that require both the central
and peripheral nervous systems be engaged, it is noted by Poole et al. (2016) that the body
experiences fatigue that can limit the body’s ability to produce the power necessary to continue
operating at an optimal level. Fatigue is something that is felt by millions of people on a daily
basis and for a variety of reasons, be it completing activities of daily living, exercising, working,
or in instances such as injury or illness. The fatigue felt during exercise is what Poole et al.
(2016) worked to address in this article, as fatigue from exercise can typically be the result of
high intensity exercise or the intensity of the power put out by the individual to complete their
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exercise and significantly impact the individual's performance. Poole et al. (2016) were clear in
their article about distinguishing between fatigue and task failure, noting that task failure is the
development of fatigue to high levels which in turn cause activity/exercise intolerance,
significantly limiting the individual's desired performance.
In the introduction of their article, Poole et al. (2016) noted the correlation between an
individual’s biological ability to function and the amount of time they spend performing certain
activities to the amount of power they are able to perform said activities with. Poole et al. (2016)
sought to provide a comprehensive synthesis of critical power from various perspectives
including the cardiovascular, neuromuscular and metabolic while taking into account both the
bioenergetic and performance-related consequences in two distinct populations of subjects:
healthy individuals and patients in the hospital who are suffering from significant diseases like
congestive heart failure and chronic obstructive pulmonary disease (COPD).
The research design of this article was qualitative, which can pose some issues in terms
of its credibility. Poole et al. (2016) utilized previously completed research data in their attempt
to show a link between the cardiovascular, neuromuscular and metabolic perspectives related to
exercise performance in healthy individuals when compared to those with chronic health
conditions. While there is a noted link to these concepts when researched in rats and other
animals, there is a weakness in the research conducted for this study, as the number of humans
utilized was minimal, the data analysis was weak, as were the conclusions that they arrived at. It
is possible that the authors could have arrived at different conclusions using a more reliable
approach in which they focused on current individuals as part of their study and data gathering
population instead of previous studies. The authors’ use of an unsystematic study using subjects
that were of advanced age and varying health levels due to chronic conditions and diseases could
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have lended well to having the necessary subjects for a control group that they would then use to
compare their study group to. The use of previous data and research, a retrospective study,
provided the authors with valuable information from what has been done in the past, which was
essential to helping readers understand fatige threshold and what that looks like in humans, was
an imperative strength for this article.
Summary
The article’s authors came to four conclusions in their study. The first conclusion Poole
et al. (2016) arrived at was that critical power, which is also noted in the article as critical speed,
and critical torque are all noted to be critical in causing a neuromuscular fatigue threshold which
leads to the separation of the domains of exercise intensity. In noting this conclusion, they did
state that there are two unknowns related to this, first is what physiological factors ultimately
cause the neuromuscular system to behave this way and if there is an overall capacity of either
torque or power output that results in a fatigue response (Poole et al., 2016).
The second conclusion that Poole et al. (2016) came to was that hyperoxia is related to an
increase in critical power as opposed to hypoxia reducing critical power. When looking at critical
power in comparison to the work that is doable above critical power (W’), there is a reduction in
the amount of doable work in hyperoxia which shows that in very intense rates of work, if the
work doable above critical power is increased, there is a decrease in the tolerance an individual
has for exercise (Poole et al., 2016). Per Poole et al. (2016), this particular set of findings is
important in that it shows the ways in which the power-duration relationship that exists for high
intensity exercise is closely linked to the skeletal muscles respiratory control. This goes to show
that critical power is what sets the limits at which VO2 is maxed out along with how inefficient
the body becomes when the muscles are fatigued and how long an individual is able to tolerate
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exercise (Poole et al., 2016). To put it in simpler terms, critical power is responsible for the
fatigue that muscles experience as well as the VO2 being maxed out for an individual while they
are participating in intense exercise.
The third conclusion that was reached through this study article was that when the work
rate is above the critical speed level, the body will recruit low oxidative Type II muscle fibers
rather than the Type I muscle fibers due to being able to operate in an environment with a lower
PO2 (Poole et al., 2016). Through this conclusion, Poole et al (2016) noted that in an individual,
critical power is easily manipulated by specific characteristics of muscle contractions.
Poole et al. (2016) came to a final conclusion through their research that critical power
acts as somewhat of a buffer in resisting intolerance of exercise during exercises categorized as
supra-CP, when the source of the buffer varies based on the conditions. The authors noted that if
the buffer is low, exercise intolerance happens at a much faster rate, causing the individual to
become fatigued much faster (Poole et al., 2016). This finding was replicatable across subjects,
with the older subjects showing similar effects of the decline of critical power and work, with
these subjects’ power duration trending downward (Poole et al., 2016). With fatigue threshold
being synonymous with critical power due to critical power being used to describe the limit by
which fatigue progresses, work could in turn be considered as a constant for how fatigued a
person gets (Poole et al., 2016).
The authors took all four of their conclusions noted throughout the article and provided a
synopsis of them in one place, noting them as the overall conclusions. Poole et al. (2016)
provided a comprehensive overview of the four individual goals that they found through their
research, making it to where readers were better able to fully understand all of the conclusions
presented.
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Conclusion
The article by Poole et al. (2016) provided information for the reader to better understand
how fatigue is intertwined with critical power and the work being done when an individual
exercises. Although the authors’ use of research related to animals to provide their comparisons
was lacking in terms of relativity, they also could have chosen study subjects that were more
closely related in terms of their demographic information. This wouldn’t have taken away from
the data provided, it would have helped to solidify their research and make the study stronger.
The use of previously researched data along with the data Poole et al. (2016) could have obtained
would have provided more concrete evidence to the concept that they were presenting. The data
that was provided did give the reader information necessary to better understand fatigue
threshold, however, connecting it to new data from more closely related subjects would have
made the information that much stronger.
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Reference
Poole, D.C., Burnley, M., Vanhatalo, A., Rossiter, H. B., & Jones, A. M. (2016). Critical power:
An important fatigue threshold in exercise physiology. Medicine and Science in Sport
and Exercise, 48(11), 2320-2334. https://www.doi.org/10.1249.MSS.0000000000000939
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