1
Case Study Essay Question: Aerobic Capacity - Autoregulation
Autoregulation refers to the intrinsic capacity of resistance vessels in an organ such as the
heart, brain, or kidneys, to maintain blood flow at a constant rate and dilate as well as constrict in
response to changes in arterial pressure. These responses occur rapidly within seconds of
fluctuations in arterial pressure and causes vasodilation. The amount of vasodilation is controlled
by the metabolic need of the muscle such as oxygen and nutrients. It occurs in arterioles and
small arteries that lead to the skeletal muscle. This allows for a control of blood flow to fit the
body’s current metabolic needs. During exercise, the skeletal muscles need a consistent flow of
blood. Autoregulation is the most important means by which blood flow to our skeletal muscles
is controlled. The blood flow is controlled by the intensity of the exercise. For lower intensity
exercise, a small amount of motor units is put into action, therefore there is a smaller demand for
blood flow to that contracting muscle or muscle groups. However, for greater intensity exercise,
there is more need for a larger number of motor units which results in the need for an increase in
blood flow to the muscle. The autoregulation is what allows the body to maintain this consistent
blood flow (Powers et al., 2021).
The three aspects of autoregulation are metabolic regulation (use of metabolic factors),
myogenic regulation (blood flow to the muscle), and neurogenic regulation. There are some
metabolic factors responsible for the autoregulation of blood flow to the skeletal muscles. The
skeletal muscle blood flow is controlled by an interaction between several parties such as nitric
oxide, ATP, adenosine, prostaglandins, and endothelium derived hyperpolarization factors. There
are local factors involved in control of the blood flow to the muscles during exercise. Since our
metabolic rate of skeletal muscle is increased during exercise, this causes increased production of
2
nitric oxide, ATP, adenosine, prostaglandins, and endothelium derived hyperpolarization factors.
Each of these has been known to promote vasodilation due to the way they increase the smooth
muscle relaxation in the arterioles. These elements all work together to cause the vasodilation of
the arterioles which feed the contracting skeletal muscles, and this is how the vasodilation leads
to reducing the vascular resistance which results in an increase in blood flow since there is less
resistance (Powers et al., 2021).
If an individual does cardiovascular training for several months consistently, this
person will notice a physiological change and improvement in their aerobic capacity.
Cardiovascular training involves exercising multiple muscle groups in a repetitive way that
elevates the individual’s heart rate and increases the oxygen as well as the blood flow throughout
the body (Powers et al., 2021). Examples of cardiovascular training include boxing, running,
swimming, rowing, dancing, jump roping, power walking, and stair climbing. Cardiovascular
(aerobic exercise) increases your energy and stamina, improves cholesterol, helps control blood
pressure, and helps you burn calories.
If an individual regularly incorporates cardiovascular training into their daily or weekly
routine, they will notice improvements in their aerobic capacity. One of the main adaptations the
body will make when someone consistently does aerobic exercise is maximal cardiac output.
This involves an increase in blood volume, increase in cardiac dimension, and a greater fill of the
ventricles. More adaptations that occur are an increase in total water, an elevation of stroke
volume, an improvement in ventricular filling, sweating responses, and increase in plasma. After
cardiovascular training for several months, the body becomes more efficient at meeting
metabolic demands (Powers et al., 2021). There are also adaptations that happen in the muscles
as well as when the body is consistently doing cardiovascular training, the body becomes
3
accustomed to the training, and it becomes easier to do as well. The results are better overall
health.
