Running head: Case Study 3
Case Study 3
Anaisha Murray
EXCS 510-B02
Liberty University
1
Case Study 3
Cardiovascular drift is observed during a prolonged exercise its when there is an
increase in heart rate as well as a decrease in stroke volume. Stroke volume is defined as the
amount of blood the heart pumps per beat. Cardiovascular drift happens when there is an
increase in body temperature on dehydration and a decrease in plasma volume[ CITATION
Pow185 \l 1033 ]. The risk of cardiovascular drift can be reduced if the athlete is staying
hydrated and biking at a lower pedal cadence[ CITATION Car \l 1033 ]. During cardiovascular
drift cardiac output can stay the same during a prolonged exercise even though compared to the
decrease in stroke volume the heart rate is increased.
It is important for an athlete to understand cardiovascular drift due to the effects that it
has on the body. According to a study done in 1992 called “Mountain SJ and Coyle EF several
athletes were monitored on an ergometer at moderate intensity for two hours in ninety one degree
weather and fifty percent humidity [ CITATION Car \l 1033 ]. The participants of this study were
divided into four controlled groups: no fluids, small fluids, moderate fluids, and large fluids over
a twenty-four hour time period before beginning the exercise. The study revealed that athletes
with the lower intake of fluids had a higher body temperature than the athletes with higher fluid
intake during the second hour of exercise. The controlled group with lower fluid intake also had
trouble regulating cardiovascular function. Over the course of the study each group experienced
a decrease in their stroke volume as well as their heart rate increasing [ CITATION Car \l 1033 ].
It has been noted that the group with the higher fluid intake were able to make up for the
decreased stroke volume and in return their cardiac output was not affected. The three less
hydrated groups began to notice a decrease in cardiac output during the third exercise session. It
has been discovered that dehydration and hyperthermia contribute to cardiovascular drift,
scientists have developed two reasons to support this theory. The first reason is that the blood
Anaisha Murray
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Case Study 3
flow in the vessels that are located in the skin causes stroke volume to decrease because of how
the blood gathers in the veins in the skin there will be less blood to circulate back to the heart
[ CITATION Car \l 1033 ]. The second reason is the increase in the heart rate results in the
decrease in stroke volume, when the heart rate increases there is less time to fill the ventricles,
resulting in decreased stroke volume.
Being hydrated before beginning an exercise is important. Hydration is responsible for
reducing cardiovascular drift by replacing the lost blood plasma to sweat and maintaining arterial
pressure. Hydrating before exercise will increase body water that helps resist changes to the core
body temperature[ CITATION Car \l 1033 ].
Understanding cardiovascular drift because cardiac output decreases as the stroke volume
decreases. Along with this there is less blood being pumped to the heart in each beat allowing the
heart to develop maximum force when fully elongated. Along with stroke volume decreasing as
cardiac output decreases blood oxygenation decreases as well, when this happens a decrease in
cerebral blood oxygenation occurs causing fatigue [ CITATION Car \l 1033 ]. For cyclers to
avoid cardiovascular drift it has been discovered that if they maintain a low pedal cadence, while
not increasing external workload the chances of experiencing cardiovascular drift is low.
Maintaining the low pedal cadence is important it blocks the passage of muscle capillaries in
active muscles during contraction. When the pedal cadence is higher the muscle capillaries have
les opportunity to fill during contractions [ CITATION Car \l 1033 ]. Thus for Mr. Froome to
reduce the risk of cardiovascular drift he should make sure he is fully hydrated before exercise
and biking at a low cadence during the exercise.
Anaisha Murray
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Case Study 3
Bibliography
Cardiovascular Drift: Another Reason to Stay Hydrated. (n.d.). Retrieved from Exercise
Medicine: http://www.exercisemed.org/research-blog/cardiovascular-drift-anothe.htmll
Powers, S. K., & Howley, E. T. (2018). Chapter Nine: Circulatory Responses to Exercise. In
Exercise Physiology: Theory & Applications to Fitness & Performance (pp. 193-223). New
York: McGraw-Hill Education
Anaisha Murray
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