The effects of low and normal dose ice slurry ingestion on endurance capacity and intestinal epithelial injury in the heat

ObjectivesCompare the effects of ice slurry ingestion at low and normal doses on endurance capacity and exertional heat stress-induced gastrointestinal perturbations.DesignRandomised, cross-over design.MethodsTwelve physically active males completed four treadmill running trials, ingesting ice slurry (ICE) or ambient drink (AMB) at 2 g·kg⁻¹ (Normal; N) or 1 g·kg⁻¹ (Low; L) doses every 15-min during exercise and 8 g·kg⁻¹ (N) or 4 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.ResultsPre-exercise gastrointestinal temperature (T_gi) was lower in L + ICE than L + AMB (p < 0.05), N + ICE than N + AMB (p < 0.001) and N + ICE than L + ICE (p < 0.001). Higher rate of T_gi rise (p < 0.05) and lower estimated sweat rate (p < 0.001) were observed in N + ICE than N + AMB. Rate of T_gi rise was similar at low dose (p = 0.113) despite a lower estimated sweat rate in L + ICE than L + AMB (p < 0.01). Time-to-exhaustion was longer in L + ICE than L + AMB (p < 0.05), but similar between N + ICE and N + AMB (p = 0.142) and L + ICE and N + ICE (p = 0.766). [I-FABP] and [LPS] were similar (p > 0.05).ConclusionsL + ICE elicited a lower heat dissipation compensatory effect with similar endurance capacity as N + ICE. Ice slurry conferred no protection against exertional heat stress-induced gastrointestinal perturbations.