Research On Cold Water Immersion Of Different Lengths Of Time To Men’s Recovery Effects After Endurance Exercise

Objective: Training and recovery after competition is an important stage for athletes to improve their competitive ability and ensure their performance.Different effective recovery methods can promote the recovery of athletes in different dimensions.Cold water immersion has become a hot topic in the international research,but the optimal intervention dose of cold water immersion is still controversial.This study is aimed at ordinary college students after endurance exercise through different duration of cold water immersion(CWI,13℃)intervention,compare the different duration of cold water immersion on the subjects’ body related physiological indicators and the recovery of the second exercise ability,by analyzing the comparative data,explore the best duration of cold water immersion intervention for different indicators.Methods: A randomized controlled design was used in this study.60 college students were randomly divided into 5 groups(5min CWI group,10 min CWI group,15 min CWI group,20 min CWI group and blank control group)with 12 students in each group.First of all,the subjects were tested with increasing load of bicycles(Starting load 50 w,incremental 50 w every 3 minutes),and then recovered in different ways according to different groups after exercise.SPSS26.0 statistical software was used to conduct single factor ANOVA test for exercise duration,squat jump height and heart rate variability measured twice before and after the restoration intervention,and pairwise paired sample T test within the group.Heart rate,blood lactic acid,blood pressure,body surface temperature,core temperature,subjective physical sensation and subjective thermal sensation were collected immediately after the first exercise,immediately after recovery intervention,10 min,20min and 30 min,and immediately after the second exercise for repeated measurement analysis of variance.Results1.In terms of exercise ability,the second exercise duration of the control group and the 5min CWI group was significantly lower than the first exercise duration(P <0.05),while the second exercise duration of the other groups was lower than the first exercise duration but had no significant change.The duration of the second exercise decreased the most in the 5min CWI group(4.49%).ED decreased the least in10 min CWI group(0.72%).After CWI intervention,the mean squat jump height was significantly decreased(P < 0.05),but there was no significant change in the control group,and the maximum squat jump height was significantly decreased in all groups(P < 0.05).2.In terms of body temperature,the body temperature of the control group increased significantly immediately after recovery(P < 0.05),while the body surface temperature of the CWI group decreased significantly immediately after the cold water intervention(P < 0.05).There was no significant difference in body surface temperature between CWI groups at the same time point.The change degree of core temperature was small,the 10 min CWI group had a significant difference between immediately after cold water intervention and 20 min after cold water intervention(P=0.004),and the 15 min CWI group had a significant difference between 10 min,20min and 30 min after cold water intervention and immediately after cold water intervention(P < 0.05).Immediately after cold water intervention,the core temperature in 20 min CWI group was significantly lower than that in CON group(P=0.029 < 0.05).3.In terms of cardiovascular,the HR of 10min-CWI,15min-CWI and20min-CWI at 45 min after exercise(72.67±8.84,72.58±3.92,70.25±8.81)was not significantly different from the baseline value,while the 5min-CWI group required55 min.The mean arterial pressure immediately after CWI intervention was significantly lower in the 10min-CWI group than that immediately after exercise(P <0.05),and the mean arterial pressure at 10 min after CWI intervention was significantly lower than that immediately after exercise in the 15min-CWI group(P <0.05).The rate of BLA decline in CWI intervention group was higher than that in control group.There was no significant difference between the BLA measured at55 min after exercise and the base value in the 20min-CWI group(P > 0.05),but the BLA measured at 55 min after exercise in the other groups was significantly greater than the base value.4.In terms of heart rate variability,no significant difference was found in HRV related indexes before and after comparison within the group.RMSSD,SDSD and HF decreased the most after 15 min CWI,SDNN and LF decreased the most after20 min CWI,and LF/HF increased the most after 15 min CWI.Conclusion:Based on the present study,at a constant water temperature of 13°C it was concluded thatDifferent lengths of coldwater immersion will have different effects on the recovery process of different indicators of the organism after endurance exercise,and an appropriate coldwater bathing program should be selected.Among them,15 min has a better effect on the recovery of body temperature;10-20 min will be more effective in promoting the recovery of blood circulation system;15 min has the best effect on the recovery of autonomic nervous system.In the application of endurance sports program 10-15 min program is more effective for the recovery of the second exercise.