Effects Of Different Precooling Methods On Incremental Cycling Exercise Performance In Hot And Humid Conditions

Objective: In reality, many sports and games are carried out at high temperature andhigh humidity environment, so conventional warm-up is adverse for the enduranceexercise in this case. Instead of conventional warm-up, precooling may be an another"warm-up" activities that is help endurance athletes resist high temperature and highhumidity, and increase the heat endurance and delaying fatigue. By having12participants cover different precooling interventions before incremental cycling exerciseperformance in hot and humid conditions, this research comparatively study the effectsof different pre-cooling methods on incremental cycling exercise performance in hot andhumid conditions, and explore proper precooling strategy being suitable for hightemperature and high humidity environment.Methods: This experiment is designed by a randomized crossover self-control. Twentyparticipants are male cyclists, mean age27.33±5.73years, mean training age3±2.50years. Each subject must perform three trials, control (CON), low body immersionprecooling (LBI) and whole body immersion precooling (WBI), which form a selfcomparison. And3subjects constitute a group in a same trial, which form a comparisonwith other groups. After20min precooling intervention, subjects immediately proceed toincremental cycling exercising to be exhausted in a environment simulation laboratory athigh temperature and high humidity environment，the temperature of35℃-38℃and60%-70%relative humidity. Related physiological indexes and performance of motiondata are acquired，and the the result of the data is analysed by SPSS20.0statisticalsoftware.Results:1. Compared with CON, exercise time, distance and workload in LBI respectivelyincreased by average of3.43minutes,1.13km, and42.89kj (P <0.05), while it is2.62minutes,0.95km and33.89kj in WBI (P <0.05).2. The LBI and WBI significantlydecreased the subjects,HR, respectively by7.3±4.0and7.0±3.3（P＜0.01）. Moreover,LBI and WBI significantly increased reserve heart rate than CON (P <0.05).3. The LBI and WBI significantly decreased the subjects,core temperature, respectivelyby0.3℃and0.4℃（P＜0.05）,and increased the Heat storage（P＜0.05）.4. At the process of exercise in high temperature and high humidity environment afterLBI and WBI, the Lac-time curve and RPE-time curve moved to the right, SpO2–timecurve was up. 5．There are significant correlations between exercise performance in high temperatureand high humidity environment and baseline HR、reserve heart rate and heat storage（P<0.01，r>0.7）Conclusions:1. The precooling method in this research can significantly reduce the HR and coretemperature, and increase the reservation of heart rate and heat storage, result inimproving athletics capacity and performance of exercise in high temperature and highhumidity environmen.2. Compared with the systemic precooling, the local precooling is more handy and lessstress. So the local precooling (low body immersion precooling) is the right strategy forthe actual high temperature and high humidity environment movement.3. The results show that precooling enhancing the exercise performance is contributed tothe baseline HR，core temperature, reserve heart rate and heat storage，but a deeperlevel of physiological mechanism fails to discuss, physiological mechanism remains tobe studied.