RESUMEN
OBJECTIVES: Compare the effects of ice slurry ingestion at low and normal doses on endurance capacity and exertional heat stress-induced gastrointestinal perturbations. DESIGN: Randomised, cross-over design. METHODS: Twelve physically active males completed four treadmill running trials, ingesting ice slurry (ICE) or ambient drink (AMB) at 2â¯g·kg-1 (Normal; N) or 1â¯g·kg-1 (Low; L) doses every 15-min during exercise and 8â¯g·kg-1 (N) or 4â¯g·kg-1 (L) pre- and post-exercise. Pre-, during and post-exercise serum intestinal fatty-acid binding protein ([I-FABP]) and lipopolysaccharide ([LPS]) concentrations were determined. RESULTS: Pre-exercise gastrointestinal temperature (Tgi) was lower in Lâ¯+â¯ICE than Lâ¯+â¯AMB (pâ¯<â¯0.05), Nâ¯+â¯ICE than Nâ¯+â¯AMB (pâ¯<â¯0.001) and Nâ¯+â¯ICE than Lâ¯+â¯ICE (pâ¯<â¯0.001). Higher rate of Tgi rise (pâ¯<â¯0.05) and lower estimated sweat rate (pâ¯<â¯0.001) were observed in Nâ¯+â¯ICE than Nâ¯+â¯AMB. Rate of Tgi rise was similar at low dose (pâ¯=â¯0.113) despite a lower estimated sweat rate in Lâ¯+â¯ICE than L+AMB (pâ¯<â¯0.01). Time-to-exhaustion was longer in Lâ¯+â¯ICE than Lâ¯+â¯AMB (pâ¯<â¯0.05), but similar between Nâ¯+â¯ICE and Nâ¯+â¯AMB (pâ¯=â¯0.142) and Lâ¯+â¯ICE and Nâ¯+â¯ICE (pâ¯=â¯0.766). [I-FABP] and [LPS] were similar (pâ¯>â¯0.05). CONCLUSIONS: Lâ¯+â¯ICE elicited a lower heat dissipation compensatory effect with similar endurance capacity as Nâ¯+â¯ICE. Ice slurry conferred no protection against exertional heat stress-induced gastrointestinal perturbations.
Asunto(s)
Temperatura Corporal , Trastornos de Estrés por Calor , Masculino , Humanos , Resistencia Física , Lipopolisacáridos , Calor , Regulación de la Temperatura Corporal , Ingestión de AlimentosRESUMEN
OBJECTIVES: We investigated the thermoregulatory responses to ice slurry ingestion during low- and moderate-intensity exercises with restrictive heat loss. DESIGN: Randomised, counterbalanced, cross-over design. METHODS: Following a familiarisation trial, ten physically active males exercised on a motorised treadmill at low-intensity (L; 40% VO2max) or moderate-intensity (M; 70% VO2max) for 75-min, in four randomised, counterbalanced trials. Throughout the exercise bout, participants donned a raincoat to restrict heat loss. Participants ingested 2gkg-1 body mass of ambient water (L+AMB and M+AMB trials) or ice slurry (L+ICE and M+ICE trials) at 15-min intervals during exercise in environmental conditions of Tdb, 25.1±0.6°C and RH, 63±5%. Heart rate (HR), gastrointestinal temperature (Tgi), mean weighted skin temperature (Tsk), estimated sweat loss, ratings of perceived exertion (RPE) and thermal sensation (RTS) were recorded. RESULTS: Compared to L+AMB, participants completed L+ICE trials with lower ΔTgi (0.8±0.3°C vs 0.6±0.2°C; p=0.03), mean RPE (10±1 vs 9±1; p=0.03) and estimated sweat loss (0.91±0.2L vs 0.78±0.27L; p=0.04). Contrastingly, Tgi (p=0.22), Tsk (p=0.37), HR (p=0.31), RPE (p=0.38) and sweat loss (p=0.17) were similar between M+AMB and M+ICE trials. RTS was similar during both low-intensity (4.9±0.5 vs 4.7±0.3; p=0.10) and moderate-intensity exercise (5.3±0.47 vs 5.0±0.4; p=0.09). CONCLUSIONS: Per-cooling using ice slurry ingestion marginally reduced thermal strain during low-intensity but not during moderate-intensity exercise. Ice slurry may be an effective and practical heat mitigation strategy during low-intensity exercise such as in occupational and military settings, but a greater volume should be considered to ensure its efficacy.