Self-paced intermittent-sprint performance and pacing strategies following respective pre-cooling and heating

This study examined the effects of pre-exercise cooling and heating on neuromuscular function, pacing and intermittent-sprint performance in the heat. Ten male, team sport athletes completed three randomized, counterbalanced conditions including a thermo-neutral environment (CONT), whole body submersion in an ice bath (ICE) and passive heating in a hot environment (HEAT) before 50 min of intermittent-sprint exercise (ISE) in the heat (31 + 1°C). Exercise involved repeated 15 m maximal sprints and self-paced exercise of varying intensities. Performance was measured by sprint times and distance covered during self-paced exercise. Maximal isometric contractions were performed to determine the maximal voluntary torque (MVT), activation (VA) and contractile properties. Physiological measures included heart rate (HR), core (T _core) and skin (T _skin) temperatures, capillary blood and perceptual ratings. Mean sprint times were slower during ICE compared to HEAT (P < 0.05). Total distance covered was not different between conditions, but less distance was covered during HEAT in 31–40 min compared to CONT, and 41–50 min compared to ICE (P < 0.05). MVT was reduced post-exercise compared to post-intervention in CONT and HEAT. VA was reduced post-intervention in HEAT compared to CONT and ICE, and post-exercise compared to ICE (P < 0.05). HR, T _core and T _skin during exercise were lower in ICE compared to CONT and HEAT (P < 0.05). Sprint times and distance covered were not affected by ICE and HEAT conditions compared to CONT. However, initial sprint performance was slowed by pre-cooling, with improvements following passive heating possibly due to altered contractile properties. Conversely, pre-cooling improved exercise intensities, whilst HEAT resulted in greater declines in muscle recruitment and ensuing distance covered.