Introduction: Pre-cooling by crashed ice is effective for improving exercise performance compare with tap water1). However, there has not been study to determine whether both pre-cooling and water replacement are improved endurance cycling performance compared with cold water. The purpose of this study was to investigate the effects of crashed ice ingestion on thermoregulatory responses and endurance cycling time in the heat. Methods: On two separate occasions, in a counterbalanced order, 9 healthy males [age = 23 ± 4 yr, height = 172.2 ± 5.0 cm, body mass = 64.0 ± 9.6 kg, maximal oxygen uptake (VO2max) = 47.7 ± 8.7 ml/kg/min] ingested 7.5 g/kg of either crashed ice (0.5°C) or cold water (6°C) before exercise and 6.0 g/kg of same drink as pre-exercise during cycling to exhaustion at 60%VO2max in the heat environment (35°C, 30% relative humidity). Rectal temperature and skin temperature, HR, VO2, sweating rate, and ratings of thermal sensation and perceived exertion were measured. Heat storage was calculated using the formula of Adams et al.2). Results and Discussion: Running time was longer after crashed ice (50.0 ± 12.2 min) compared with cold water ingestion (42.2 ± 10.1 min). Before cycling performance, rectal temperature decreased 0.37 ± 0.03°C after crashed ice ingestion compared with 0.17 ± 0.02°C with cold water and remained lower for the first 30 min of exercise. After crashed ice ingestion, heat storage capacity increased (-7.61 ± 4.21 W/m2) compared with cold water (-2.18 ± 3.18 W/m2). However, rating of change occurring in rectal temperature during cycling performance did not reach significance. These results suggest that endurance cycling performance improved because of decreased rectal temperature and heat storage immediately before exercise compared with cold water ingestion. Conclusions: Compared with cold water, both pre-cooling and water replacement by crashed ice ingestion dropped rectal temperature at pre-exercise and remained lower during exercise. Moreover, crashed ice ingestion increased endurance cycling time in the heat. As such, crashed ice ingestion may be an effective and practical pre-cooling and water replacement maneuver for athletes competing in heat environment.
© Copyright 2014 19th Annual Congress of the European College of Sport Science (ECSS), Amsterdam, 2. - 5. July 2014. Veröffentlicht von VU University Amsterdam. Alle Rechte vorbehalten.