Practical precooling: effect on cycling time trial performance in warm conditions

Area of Science:

• Sports Science
• Exercise Physiology
• Environmental Physiology

Background:

• Athletes often face performance decrements in warm environments due to heat stress.
• Precooling techniques aim to lower core body temperature before exercise to mitigate heat strain.
• Practical and effective precooling strategies are crucial for optimizing athletic performance in the heat.

Purpose of the Study:

• To compare the efficacy of two practical precooling methods: skin cooling (cooling jacket) versus combined skin and core cooling (water immersion + cooling jacket).
• To assess the impact of these precooling techniques on laboratory cycling time trial performance in warm conditions.

Main Methods:

• Six trained cyclists performed a VO2(peak) test and four cycling time trials in a heat chamber (34.3°C, 41.2% rh).
• Precooling interventions included a control (no cooling), cooling jacket alone, and a combined water immersion followed by a cooling jacket.
• Rectal temperature was monitored, and time trial performance was measured.

Main Results:

• The combined precooling strategy significantly reduced pre-time trial rectal temperature compared to control and jacket-only conditions (P < 0.01).
• Time trial performance was significantly faster with combined precooling (-42 ± 25 s, P = 0.009) but not with the cooling jacket alone (-16 ± 36 s, P = 0.35) compared to the control.
• The reduction in rectal temperature achieved by combined precooling persisted throughout the warm-up and time trial.

Conclusions:

• A practical combined precooling strategy (water immersion + cooling jacket) effectively lowers core body temperature.
• This combined precooling approach significantly improves cycling time trial performance in warm environments.
• Combined precooling offers a viable method for athletes to enhance endurance exercise capacity in the heat.