Introduction: Both warm-up and precooling have proved to be beneficial for exercise performance. However, it remains unclear which preparation regime is optimal for endurance exercise in conditions of high environmental heat stress. Especially the combination of internal and external cooling can have beneficial effects on performance by lowering body heat content and creating a sensation of coolness. Therefore, the aim of this study was to analyse the effect of different preparation regimes on pacing and performance during a 15-km cycling time trial in the heat. Methods: Ten male subjects (24±5yrs) completed four 15-km time trials (30°C, 50% relative humidity), preceded by different preparation regimes: 10 min cycling at 2 W/kg BM (WARM/UP), 30 min scalp cooling of which 10 min cycling at 2 W/kg BM (WARM/UP+SC), 2g/kg BM ice slurry ingestion (COOL), and 2g/kg BM ice slurry ingestion + 30 min scalp cooling (COOL+SC). During the trials, power output (PO), rectal (Tre) and skin (Tsk) temperature, thermal sensation (TS), heart rate (HR) and RPE were measured. Results: Tre at the start of the time trial was lower (P<0.05) for COOL+SC (36.7±0.2°C) and COOL (36.8±0.3°C) than for WARM/UP (37.2±0.3°C) and WARM/UP+SC (37.1±0.3°C). Tsk and TS were lower at the start for COOL+SC than for the other conditions (mean difference Tsk: 0.7±0.4°C; P<0.05). During the time trial, a main difference in Tre was found between WARM/UP+SC and both COOL and COOL+SC (P<0.05). Tsk was lower for COOL+SC than for WARM/UP (P<0.05). Differences in Tre and Tsk between precooling and warmup were significant during the first part of the time trial. No differences were found in finish time (P=0.28) and mean PO (P=0.32), although PO was higher for COOL+SC during the final part of the time trial (km 13-14; P<0.05). HR was significantly higher for WARM/UP (170±9) than for WARM/UP+SC (165±10; P=0.04). No overall effect of RPE was observed (P=0.19). Discussion: Main finding of this study is that precooling by ice slurry ingestion and scalp cooling before the start of a 15-km cycling time trial after is beneficial for performance in the latter stages of the trial, although physiological and perceptual changes have completely disappeared at that moment. This indicates that internal and external cooling before the start of endurance exercise in the heat should be preferred over warming-up, especially since a higher work rate near the finish may be of great benefit in practice, when inter-individual differences are small.
© Copyright 2012 17th Annual Congress of the European College of Sport Science (ECSS), Bruges, 4. -7. July 2012. Julkaistu Tekijä Vrije Universiteit Brussel. Kaikki oikeudet pidätetään. / Kääntänyt https://www.DeepL.com/Translator