Importance of airflow for physiologic and ergogenic effects of precooling

Abstract

Context: Cooling the body before exercise (precooling) has been studied as an ergogenic aid for many thermal conditions; however, airflow accompanying exercise is seldom reported. Objective: To determine whether the physiologic and ergogenic benefits of precooling before endurance exercise may be negated with semirealistic airflow in hot conditions. Design: Crossover study. Setting: Climate-controlled chamber in a research laboratory. Patients or Other Participants: Ten fit, healthy cyclists. Intervention(s): After a familiarization trial, participants completed 4 randomized, counterbalanced sessions consisting of no precooling versus precooling and no fan airflow versus airflow (∼4.8 m/s) during exercise. Precooling was via chestdeep immersion (∼24 °C) for 1 hour or until core temperature dropped 0.58C. Participants then cycled at 95% ventilatory threshold in a hot environment (temperature = 30°C, relative humidity = 50%) until volitional exhaustion, core temperature reached >39.5°C, or heart rate reached >95% of maximum. Main Outcome Measure(s): Thermal strain was assessed via core temperature (esophageal and rectal thermistors) and mean skin temperature (thermistors at 10 sites) and cardiovascular strain via heart rate and ratings of perceived exertion. Results: Endurance time (28 - 12 minutes without precooling or airflow) increased by 30 - 23 minutes with airflow (∼109%; 95% confidence interval = 12, 45 minutes; P