Question

Exercising in environments with high ambient temperatures will affect performance by

a. Requiring more oxygen to perform the same amount of work

b. Requiring more cardiac output to working muscles to perform the same amount of work

c. Compromising stroke volume

d. Reducing peak heart rate

e. None of the above

Answer 1

Option C is the correct answer.

In hot environments, the core-to-skin temperature gradient is less than in cool environments, so that skin blood flow must be relatively high to achieve sufficient heat transfer to maintain thermal balance. This high skin blood flow causes pooling of blood in the compliant skin veins, especially below heart level. In addition, as discussed, sweat secretion can result in a net loss of body water, and thereby a reduction in blood volume.Compensatory responses include reductions in splanchnic and renal blood flow; increased cardiac contractility, which helps to defend stroke volume in the face of impaired cardiac filling; and increased heart rate to compensate for decreased stroke volume.