The effect of precooling on exhaustive performance in the hot environment

Background: Pre-cooling is known to enhance exercise performance in soccerplayers. However, little information currently exists regarding precooling effects in Iranian young soccer players. Objectives: The aim of this study was to assess the effect of precooling (water immersion) on exhaustive performance in the heat (temperature =32-34°C, humidity = 50%). Patients and Methods: Sixteen young male soccer players from the provincial competitive teams were divided into two equal groups and were randomly assigned to precooling (age =16.5 ± 1.1 year, height = 171.7 ± 6.4 cm, BMI = 21.5 ± 3.3, V[O.sub.2max] = 50.6 ± 6.9 mL/kg/min) and non-precooling (age = 16.1 ± 1.1 year, height = 170.0 ± 4.7 cm, BMI = 21.3 ± 3.6, V[O.sub.2max] =50.6 ± 6.8 mL/kg/min) groups. An exhaustive treadmill run test was conducted after warm-up (non-precooling) or warm-up + water immersion (temperature = 22-24°C). Oral temperature, plasma lactate and plasma volume were measured at the baseline (fasting state), mid test (immediately after warm up or warm-up + water immersion) and post test (immediately after exhaustive test). Mixed repeated measures analysis of variance and independent t test were used for data analyzing. P< 0.05 was considered significant. Results: There were no significant differences between two groups at baseline, mid test and post test regarding oral temperature and plasma lactate. The time to exhaustion was considerably higher in the precooling group compared with the non- precooling group, but the difference was not statistically significant. No significant differences were found between the two groups on measures of the baseline and mid test plasma volume, but post test plasma volume was significantly higher in the precooling group compared to the non-precooling group (P < 0.05). Conclusions: These results show that precooling effectively attenuates dehydration, but has no positive effect on exhaustion time in the hot environment. Keywords: Heat Temperature, Exercise, Plasma Volume