Comparison of the effects of cold water and ice ingestion on endurance cycling capacity in the heat

AbstractPurposeThe purpose of this study was to examine the effects of pre-cooling and fluid replacement with either crushed ice or cold water.MethodsOn two separate occasions, in a counterbalanced order, nine recreationally-trained males ingested 1.25 g/kg (80–100 g) of either crushed ice (0.5°C) or cold water (4°C) every 5 min for 30 min before exercise. They also ingested 2.0 g/kg (130–160 g) of the same treatment drink at 15, 30, and 45 min after the commencement of cycling to exhaustion at 60%VO2max until voluntary exhaustion in a hot environment (35°C and 30% relative humidity).ResultsThe cycling time to exhaustion in the crushed ice trial (50.0 ± 12.2 min) was longer than the cold water trial (42.2 ± 10.1 min; p = 0.02). Although the rectal temperature fell by 0.37°C ± 0.03°C (p = 0.01) at the end of the resting period after the crushed ice ingestion, the rates of rise in rectal temperature during the exercise period were not significantly different between these two conditions (crushed ice: 0.23°C ± 0.07°C, 5 min; cold water: 0.22°C ± 0.07°C, 5 min; p = 0.94).ConclusionCrushed ice ingestion before and during exercise in a hot environment may be a preferred and effective approach for minimizing thermal strain, and for improving endurance performance as compared with cold water ingestion