Impact of upper body precooling during warm-up on subsequent time trial paced cycling in the heat.

Objectives: The purpose of this study was to test the hypothesis that cooling the upper body during a warm-up enhances performance during a subsequent 16.1-km simulated cycling time trial in a hot environment.

Design: Counterbalanced, repeated measures design.

Methods: Eight trained, male cyclists (peak oxygen uptake=57.8±5.0mLkgmin) completed two simulated 16.1-km time trials in a hot environment (35.0±0.5°C, 43.8±2.0% relative humidity) each separated by 72h. Treatments were counterbalanced; participants warmed up for 20min while either wearing head and neck ice wraps and an ice vest (COOLING) or no cooling apparatus (CONTROL).

Results: Following the warm-up mean skin temperature (T¯), mean body temperature (T¯) and rating of thermal comfort were significantly lower than baseline following the COOLING trial (all P<0.05); however, rectal temperature was unaffected (P=0.35). Because the effects of precooling on T¯ and T¯ were not sustained during exercise, values for COOLING and CONTROL were not different throughout the time trial (P=0.38). Nonetheless, time to completion was significantly faster following the COOLING intervention when compared to the CONTROL (29.3±3.6min, vs. 30.3±3.1min; P=0.04).

Conclusions: These data suggest that in short distance time trials in hot conditions cyclists may benefit from utilizing a cooling modality during the warm-up.