| Background: In sports practice,athletes and practitioners are increasingly using cold water immersion to relieve post-exercise fatigue and accelerate the recovery of physiological function and athleticism.Previous studies have used a variety of coldwater immersion protocols with different combinations of water temperature and time to achieve some efforts of recovery,but the appropriate cold water immersion protocol for short-term recovery is still difficult to determine,and the relatively good recovery is to be sought under conditions that control for the different combinations of water temperature and time in different cold water immersion protocols.The effects of recovery are specific to the needs of different exercise types,whereas the exercise protocols selected in previous studies are more homogenous and less representative.In this study,three cold water immersion protocols with different combinations of water temperature and time are selected as recovery methods after endurance-type and sprinttype exercise to explore their short-term recovery effects on physiological function and exercise performance.Purpose: Based on the previous studies,this study will compare the effects of different combinations of water temperature and time in cold water immersion protocols and passive recovery on the recovery of physiological functions and the ability to reexercise within a short period of time after one-time endurance-type and sprint-type exercise,and explore their mechanisms to provide reference for the practical application of cold water immersion.Methods: The literature method,experimental method and mathematical-statistical method are used to collate the available literature and to carry out experimental studies based on the results of existing research.In this study,24 non-sports major college students are recruited and randomly divided into two groups with 12 subjects in each group.Each subject is required to participate in 4 experiments.One group of subjects participate in endurance-type exercise.The exercise protocol is cycle ergometer graded exercise test.The initial power for cycling is 50 w,increasing by 50 w every 3min,and the revolutions are maintained between 55-65 RPM until the subject cannot maintain the prescribed revolutions,that is,the end of the exercise.Another group of subjects participate in sprint-type exercise,which is the Wingate test protocol,cycling at full power for 30 s with resistance of 0.075kg/kg·BW.Basic information are collected from subjects before the experiment,including age,height,weight,body fat percentage and body mass index.In the formal experiment,subjects rest quietly for 15 minutes after arriving at the laboratory,and then basic values are collected including HR,SV,CO,PI,Tc,Tsk.During the 1h recovery process after the exercise,each subject adopts one recovery protocol.The recovery protocols are passive recovery protocol and three cold water bath protocols,namely CON(PAS),C1(15°C,15 min),C2(10°C,10 min)and C3(10°C,15 min).In the recovery stage,HR,SV,CO,PI,Tc,Tsk are collected at the 5,10,15,and 60 min.Omegawave body function test is conducted during the 15 to 45 min of the recovery to record the activities of sympathetic nerve and vagus nerve regulatory mechanisms.The exercise protocol is repeated again after the recovery stage,and HR,SV,CO,PI,Tc,Tsk are collected at the end of the exercise.Results: Endurance-type exercise protocol: At the 5 min of the recovery stage,PI of C2 group was 11.38±6.03,significantly higher than that of CON group 4.88±2.45(P<0.05);PI of C3 group was 14.14±2.84,significantly higher than that of C1 group 9.25±3.40(P<0.05)and CON group 4.88±2.45(P<0.01).At the 10 min of the recovery stage,Tsk of CON group was 33.84±0.67?,significantly lower than that of C1 group 34.97±0.94?(P<0.05).At the 15 min of the recovery stage,Tsk of CON group was 33.55±0.79?,significantly lower than that of C1 group 35.05±0.70?(p<0.05)and that of C2 group 35.32±0.40? and that of C3 group 35.27±0.91?(p<0.01).At the 60 min of the recovery stage,CO of C2 group was 7.20±1.27 l,significantly higher than that of C1 group 5.55±0.85l(p<0.05);PI of C2 group was 4.30±0.40,significantly higher than that of C3 group 1.17±0.49(p<0.05);Tsk of CON group was 33.50±1.10?,significantly higher than that of C3 group 34.57±0.60?(p<0.05).The Asym of C2 group was 0.41±0.07,significantly higher than that of CON group 0.19±0.05 and that of C1 group 0.19±0.08 and that of C3 group 0.20±0.09(p<0.01).The Avag of C2 group was 24.83±14.50,significantly lower than that of CON group 56.14±19.14(p<0.01)and that of C1 group 55.42±13.67(p<0.01)and that of C3 group 43.16±27.72(p<0.05).The second exercise duration of CON group was 619.71±87.77 s,significantly less than that of C1 group 646.57±104.92s(p<0.05).Sprint-type exercise protocol: At the 10 min of the recovery stage,PI of C2 group was 8.01±2.08,significantly higher than that of CON group 4.18±1.68 and that of C1 group 4.05±1.96(P<0.05).At the 15 min of the recovery stage,CO of CON group was 6.66±0.63,significantly lower than that of C3 group 8.08±0.91l(p<0.05);PI of C2 group was 5.07±1.91,significantly higher than that of C1 group 3.08±1.63(p<0.05).Peak power for the second exercise of CON group was 827.47±93.79 w,significantly lower than that of C1 group 773.51±43.78 w and that of C2 group 765.88±69.01 w and that of C3 group 777.08±58.94w(p<0.05).No significant differences were found among the remaining 4 groups at each time point for the remaining indicators.Conclusion: 1.Different combinations of time and water temperature in cold water immersion have different effects for post-exercise recovery,especially for different types of exercise,should choose the appropriate cold water immersion protocol for different exercise.2.Cold water immersion with higher temperature and longer time is adopted recovery after endurance exercise,which is conducive to the recovery of exercise ability.The cold water immersion with lower temperature and shorter time is more conducive to the recovery of physiological and nervous system functions after exercise,so the corresponding combination of temperature and time should be selected according to different needs.3.Cold water immersion has inhibitory effect on the second peak power of sprint-type exercise,and the lower the temperature is,the more obvious the inhibition is.Cold water immersion should not be used before and during the interval of two exercise. |
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