Ice slurry ingestion lowers thermoregulatory strain in wheelchair tennis players during repeated sprint intervals in the heat

Purpose: To examine the efficacy of per-cooling via ice slurry ingestion (ICE) in wheelchair tennis players exercising in the heat.

Methods: Eight wheelchair tennis players undertook sprints (4 sets of 10 × 5 s over 40 min) in a hot environment (~32^oC), interspersed by three boluses of 2.67 g∙kg (6.8 g∙kg total) ICE or drinking temperate water (CON). Athletes performed an on-court test of repeated sprint ability (20 × 20 m) in temperate conditions immediately before and 20 min after the heat exposure whereby time to complete each sprint, as well as intermediate times, was recorded. Gastrointestinal, weighted mean skin and forehead temperature were collected throughout the heat exposure, as were thermal sensation, heart rate and blood lactate concentration. Sweat rate was calculated from body mass changes and fluid/ice intakes.

Results: Compared to CON, ICE resulted in a significantly lower gastrointestinal temperature (95% confidence intervals: 0.11, 0.17^oC; p < 0.001), forehead temperature (0.58, 1.06^oC; p < 0.001), thermal sensation (0.07, 0.50 units; p = 0.017) and sweat rate (0.06, 0.46 l∙h^-1; p = 0.017). Skin temperature, heart rate and blood lactate concentration were not significantly different between conditions (p ≥ 0.598). There was no overall change pre- to post-heating (p ≥ 0.114) nor effect of condition (p ≥ 0.251) on repeated sprint times.

Conclusions: ICE is effective at lowering objective and subjective thermal strain when consumed between sets of repeated wheelchair sprints in the heat. However, ICE had no effect on on-court repeated 20 m sprint performance.