The Effects of Differences in the Timing of Ice Ingestion Before Exercise on Endurance Cycling Capacity, Body Temperature and Perceptual Sensation in the Heat

The timing at which ice is ingested prior to exercise may be important for optimizing internal pre-cooling effects. However, previous reports have not evaluated the influence of timing of ice ingestion on internal pre-cooling in the heat. The purpose of this study was to investigate the effects of differences in the timing of ice ingestion on endurance cycling capacity, body temperature and perceptional sensation during heat stress. Seven healthy males [age=26±2 yr, height=1.71±0.04 m, body mass=63.6±2.8 kg, surface area=1.74±0.03 m2, VO2max=49.7±4.4 ml･kg−1･min−1] ingested ice for 30 min before exercise under 3 separate conditions: ice ingestion at 30-(30D), 15-(15D) and 5-(5D) minute intervals. The total volume of ice ingestion was identical during 30D, 15D, 5D and was divided equally by the number of times drunk in each experiment. Subjects performed cycling to exhaustion at 70%VO2max in a hot environment (35℃ room temperature and 30% relative humidity). Rating of thermal sensation was lower in the 5D group at 15 min period during exercise than those under the other conditions (p