Cardiovascular responses to hot skin at rest and during exercise

Area of Science:

• Cardiovascular Physiology
• Exercise Physiology
• Thermoregulation

Background:

• Integrative cardiovascular responses to heat stress during endurance exercise are complex.
• Skin temperature is a key variable influencing these responses, particularly above 38°C.
• Exercise intensity modulates the cardiovascular system's adaptation to heat stress.

Purpose of the Study:

• To review how elevated skin temperature affects the cardiovascular system during submaximal endurance exercise.
• To elucidate the role of exercise intensity in cardiovascular adjustments to hot skin conditions.

Main Methods:

• Review of current scientific literature on cardiovascular responses to heat stress during exercise.
• Analysis of physiological mechanisms altering skin blood flow, venous tone, heart rate, and stroke volume.

Main Results:

• At rest and low-intensity exercise, hot skin increases skin blood flow and abolishes cutaneous venous tone, leading to blood pooling but maintaining cardiac output via increased heart rate.
• During moderate to intense exercise, hot skin may not abolish cutaneous venoconstriction due to sympathetic activity.
• Hot skin reduces stroke volume during intense exercise by decreasing ventricular filling time, thus limiting cardiac output elevation.

Conclusions:

• Exercise intensity is a critical determinant of cardiovascular responses to hot skin during endurance exercise.
• At low intensities, the cardiovascular system can compensate for hot skin effects to maintain cardiac output.
• At higher intensities, hot skin impairs stroke volume and limits the ability to increase cardiac output, impacting physiological regulation.