The influence of ice slurry ingestion on maximal voluntary contraction following exercise-induced hyperthermia

The purpose of this study was to determine whether ingestion of a small bolus of ice slurry (1.25 g kg(-1)) could attenuate the reduction in maximal voluntary isometric contraction (MVC) torque output during a 2-min sustained task following exercise-induced hyperthermia. On two separate occasions, 10 males (age: 24 +/- A 3 years, VO2peak: 49.8 +/- A 4.7 ml kg(-1) min(-1)) ran to exhaustion at their first ventilatory threshold in a hot environment (34.1 +/- A 0.1A degrees C, 49.5 +/- A 3.6% RH). Prior to and after exercise, subjects performed a 2-min sustained MVC of the right elbow flexors in a thermoneutral environment (24.6 +/- A 0.8A degrees C, 37.2 +/- A 4.5% RH). The post exercise MVC was performed immediately following the ingestion of either 1.25 g kg(-1) of ice slurry (-1A degrees C; ICE) or warm fluid (40A degrees C; CON), in a counterbalanced and randomised order. Run time to exhaustion (42.4 +/- A 9.5 vs. 41.7 +/- A 8.7 min; p = 0.530), and rectal (39.08 +/- A 0.30 vs. 39.08 +/- A 0.30A degrees C; p = 0.934) and skin temperatures (35.26 +/- A 0.65 vs. 35.28 +/- A 0.67A degrees C; p = 0.922) and heart rate (189 +/- A 5 vs. 189 +/- A 6 beats min(-1); p = 0.830) at the end of the run were similar between trials. Torque output during the post-exercise 2-min sustained MVC was significantly higher (p = 0.001) following ICE (30.75 +/- A 16.40 Nm) compared with CON (28.69 +/- A 14.88 Nm). These results suggest that ice slurry ingestion attenuated the effects of exercise-induced hyperthermia on MVC, possibly via internal thermoreceptive and/or temperature-related sensory mechanisms.