Repeated-sprint exercise delays gastric emptying independently of hypoxia and heat exposure

PURPOSE: The present study examined the effects of repeated-sprint exercise in normoxia, hypoxia, and combined heat and hypoxia on the gastric emptying rate. METHODS: Eleven physically active males completed four experimental trials, consisting of a resting control (REST) and three exercise trials; three sets of 5 × 6-s maximal sprints in normoxia (NOR; 23℃, FiO2: 20.9%), hypoxia (HYP; 23℃, FiO2: 14.5%), and combined heat and hypoxia (HH; 35℃, FiO2: 14.5%) in a randomized order. Post-exercise gastric emptying rate was assessed by the 13C-sodium acetate breath test. RESULTS: The 13C excretion was significantly lower in the exercise trials (NOR, HYP, and HH) than in the REST during 10-35 min after exercise (p < 0.05). Time to peak 13C excretion was significantly delayed in all exercise trials (NOR, HYP, and HH) compared with the REST (p < 0.05), with no difference among the exercise trials. The magnitude of the gastric emptying delay was correlated with power output and blood glucose during the exercise. CONCLUSION: Repeated-sprint exercise significantly delayed gastric emptying, while additional hypoxic or heat stress did not exacerbate the delay, suggesting that hypoxic or heat stress can be applied during repeated-sprint training without negative impacts on gastric emptying.