Effects of precooling on thermoregulation during subsequent exercise

Area of Science:

• Exercise Physiology
• Environmental Physiology
• Sports Science

Background:

• Athletes often use precooling to manage thermal strain during exercise.
• Understanding the efficacy of precooling in triathlon simulations is crucial for performance optimization.
• Warm environments pose significant challenges to thermoregulation during endurance events.

Purpose of the Study:

• To investigate the impact of precooling on body core temperature during a simulated triathlon.
• To determine if precooling can reduce thermal strain and enhance exercise tolerance in a warm, humid environment.
• To assess the transient effects of precooling on physiological and subjective responses in triathletes.

Main Methods:

• Six trained triathletes underwent two randomized trials: a precooling trial (PC) and a control trial (CON).
• Precooling involved reducing rectal temperature (Tre) by 0.5°C in cool water before a 15-minute swim and 45-minute cycle.
• Physiological (Tre, heart rate, oxygen uptake) and perceptual (RPE, thermal sensation) data were collected throughout the simulated triathlon.

Main Results:

• Precooling transiently attenuated the rise in rectal temperature during the initial stages of cycling.
• No significant differences were observed in heart rate, oxygen uptake, skin temperature, or thermal sensation between trials.
• Body heat storage during cycling was significantly greater in the precooling trial compared to the control trial.

Conclusions:

• Precooling offers a temporary reduction in core body temperature but does not enhance overall exercise tolerance in this simulated triathlon.
• The transient nature of the precooling effect suggests limited practical benefit for triathletes in similar warm conditions.
• Further research may explore different precooling methods or durations for potential benefits in endurance events.