Prolonged self-paced exercise in the heat - environmental factors affecting performance.

ABSTRACTIn this review we examine how self-paced performance is affected by environmental heat stress factors during cycling time trialperformance as well as considering the effects of exercise mode and heat acclimatization. Mean power output during prolonged cycling time trialsin the heat (≥30°C) was on average reduced by 15% in the 14 studies that fulfilled the inclusion criteria. Ambient temperature per se was a poor predictor of the integrated environmental heat stress and 2 of the prevailing heat stress indices (WBGT and UTCI) failed to predict the environmental influence on performance. The weighing of wind speed appears to be too low for predicting the effect for cycling in trained acclimatizedsubjects, where performance may be maintained in outdoor time trialsat ambient temperatures as high as 36°C (36°C UTCI; 28°C WBGT). Power output during indoor trials may also be maintained with temperatures up to at least 27°C when humidity is modest and wind speed matches the movement speed generated dur...