Human behavioral thermoregulation during exercise in the heat.

Area of Science:

• Exercise Physiology
• Environmental Physiology
• Human Performance

Background:

• Prolonged exercise performance is significantly impaired in hot environments.
• Behavioral aspects of thermoregulation are critical determinants of exercise capacity in the heat.
• Understanding voluntary control of exercise intensity is key to mitigating heat stress during physical activity.

Purpose of the Study:

• To review and interpret existing knowledge on the voluntary control of exercise work rate in hot environments.
• To elucidate the perceptual and physiological factors mediating exercise adjustments in the heat.
• To differentiate thermal behavior during exercise from that during rest.

Main Methods:

• Systematic review and interpretation of published research on exercise in hot environments.
• Analysis of studies investigating voluntary reductions in exercise intensity.
• Evaluation of the roles of thermal perception, thermal comfort, and rating of perceived exertion.

Main Results:

• Voluntary decreases in exercise work rate in uncompensable heat act as thermoregulatory behaviors.
• Rating of perceived exertion is the primary controller of exercise intensity in the heat, with thermal perception playing a modulatory role.
• Early heat exposure (elevated skin temperature) involves thermal perception influencing perceived exertion; later stages (elevated core and skin temperature) involve cardiovascular strain dictating perceived exertion.

Conclusions:

• Voluntary exercise modifications in the heat are crucial for thermoregulation.
• The control of exercise intensity in the heat shifts from thermal perception to cardiovascular strain as heat stress intensifies.
• Rating of perceived exertion is a central mediator of behavioral thermoregulation during exercise in hot conditions.