Myocardial functional responses do not contribute to maximal exercise performance in the heat

摘要

BackgroundBoth the extent and means by which maximal oxygen uptake (V˙O2max) is depressed by elevated ambient temperature are uncertain. Particularly, information is currently unavailable regarding the possible influence of alterations in myocardial function on V˙O2max and performance during exercise in the heat. This study investigated the effects of environmental heat on V˙O2max, peak work capacity, and myocardial function during a standard, progressive cycle test to exhaustion. Twelve euhydrated men (aged 20.7 ± 1.7 years) performed a maximal cycle test in an environmental chamber in both heat stress [35°C, 30% relative humidity (RH)] and temperate (20°C, 30% RH) conditions with measurement of standard gas exchange variables, core temperature, and echocardiographic measures of cardiac function.