Cold drink attenuates heat strain during work-rest cycles.

Area of Science:

• Exercise Physiology
• Environmental Heat Stress
• Human Thermoregulation

Background:

• Limited data exists on the thermoregulatory impact of cold drink ingestion post-exercise.
• Understanding fluid temperature effects is crucial for heat acclimatization strategies.

Purpose of the Study:

• To investigate the thermoregulatory effects of ingesting cold (4°C) versus warm (28°C) drinks during exercise in the heat.
• To assess the impact on core and skin temperatures, heart rate, and subjective thermal sensation.

Main Methods:

• Eight healthy males completed two treadmill exercise-rest cycles in heat.
• Participants ingested 400mL of water at either 4°C or 28°C during rest periods.
• Measured rectal temperature, skin temperature, heart rate, and thermal sensation ratings.

Main Results:

• Cold drinks led to a greater decrease in rectal temperature (0.5°C vs 0.3°C) and a faster decrease in skin temperature.
• Mean heart rate was lower, and thermal sensation ratings were reduced after cold drink ingestion.
• The reduction in rectal temperature with cold drinks was less than anticipated.

Conclusions:

• Ingesting cold drinks post-exercise aids thermoregulation by reducing core and skin temperatures and heart rate.
• Cold drinks may offer benefits for work tolerance in hot occupational and military settings.
• Further research is needed to optimize cold fluid intake for heat management.