Short term pre-cooling maneuvers - effect on dehydration and thermoregulation during an exercise test in the warm environment

Abstract

Background. Long period of pre-cooling reduces heat stress and leads to performance improvement in warm environments. This study examined the effectiveness of the shorter period of pre-cooling using cold water immersing or cold shower exposure on hydration status and thermoregulation in the heat condition (temperature=32-34°C, humidity=50%).
Material and Method. Twenty four volunteer young male soccer players were randomly divided into three groups. The groups completed 45 minutes of treadmill running test either after warm up (non-pre-cooling group, n=8, VO_{2max, ml/kg/min}=50.69± 5.68), or after warm up+ 10 minutes of cold water immersion (cold water immersion group, n=8, VO_{2max, ml/kg/min} =50.62± 6.90), and or after warm up+ 2 minutes of cold shower (cold shower group, n=8, VO_{2max, ml/kg/min} = 51.16± 5.92). Oral temperature, plasma lactate, K, and Na were measured at rest (pre test), after (mid test) warm- up or pre-cooling, and after exercise test (posttest). Plasma volume and dehydration were calculated using related formulas.
Results. Post test oral temperature and plasma lactate were significantly (P≺0.05) higher, while post test body weight was significantly (P≺0.05) lower than the pre test in the study groups. No significant differences between the three groups were found for oral temperature, plasma volume, dehydration status, plasma lactate, K and Na at the post test.
Conclusion. Based on these results, it can be said that there is no evidence for the positive effect of the short time pre-cooling methods on thermoregulation and dehydration during exercise in the heat condition. This trial is registered with Iranian Registry of Clinical Trial (IRCT) number IRCT2015121325503N1.

Key words:

hot temperature, plasma volume, dehydration, body temperature, young soccer players

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