| 1、ObjectiveThis study aimed to investigate the influence of using precooling methods on the ability of sports and the perfoamance of matchs in hot/humidity environment. Using the human experiment design, to compare the impact of different precooling measures on the capacity of exercise and the function of physiological in hot/humidity condition, in order to attempt to explore differents of precooling measures for improving sports ability and improve the effects of physiological functions, to provide important experimental data preparation for Rio DE janeiro Olympic Game which would be hold on in Brazil. At the same time, the most effective means of precooling will be recommended to be applied in training and sports, and will help coaches and athletes to improve the athletic ability and performance in training and matches. 2、MethodsRecruit 10 male football(Rugby) team sports player as subjects who came from the rugby team of Chinese Agricultural school, using the repeated experiment design, totally completed four experimental conditions in hot/humid conditions(temperature 38℃, 50% humidity): initially involving a 30-min precooling period consisting of either nothing to control(CONT, C); wear a cooling vest(V); ingestion of an ice beverage(I); or the mix method of combination of wearing a cooling vest and ingestion of ice beverage(V+I, M). Each conditions of different Experiments are separated 7 days, the intervention stage is in the environment of hot/humid conditions(temperature 38℃, 50% humidity) to make warm up in 30 minutes for the exhaustion exercise of running, meanwhile, the precooling measures would be used.Control group(CONT, C) intervene nothing to subjects; Cooling vest group(V) wear a Cooling vest in 4℃ for 30 minutes to prepare for warming up at the same time; Ice beverage ingestion group(I) drink 2.3 ml /kg of body weight of 4℃ sports beverage drinks every 10 minutes in 2 minutes as soon as possible, drinking a total of 3 times; The mix method of compound group(V+I, M) wearing a cooling vest in 4℃and ingestion of ice beverage which drink 2.3 ml/kg of body weight of 4℃ sports beverage drinks every 10 minutes in 2 minutes as soon as possible, drinking a total of 3 times superposition use at the same time. Following this, testing phase in the same environment temperature under interspersed with sub-maximal exercise(80% of VO2 Max strength) of treadmill test, until athletes exhausted. During the experiment, the before and after of the intervention measuring and the exhaustion of the core temperature, heart rate, body temperature, RPE/RPB, the rating of thermal sensation, movement time and movement distance must be test and carry on the detailed record. 3、ResultThe running distance of the cooling vest(V), the ice beverage(I) and the mix method(M) has a very significant increase(P≤0.01) compared with the control(CONT, C), the running distance of the mix method(M) and the cooling vest(V) and the ice beverage(I) has significant increase(P≤0.05) than the control(CONT, C). The cooling vest(V) compared with the ice beverage(I) has no significant difference. The exhaustion time of the cooling vest(V) compared with the control(CONT, C) had significant increase(P≤0.05), the exhaustion time of the mix method(M) compared with the control(CONT, C) has a very significant increase(P≤0.01), the mix method(M) compared with the cooling vest(V) and the ice beverage(I) has no significant difference. The peak oxygen uptake of each movement of exhaustion were no significant difference between each others.The heart rate of before and after the precooling and after exercise between each of different conditions were no significant difference. The change rate of heart rate ratio of the cooling vest(V), the ice beverage(I) compared with the control(CONT, C) had significantly lower(P≤0.05), the change rate of heart rate ratio of the mix method(M) compared with the control(CONT, C) has a very significant decrease(P≤0.01). The change rate of heart rate ratio of the cooling vest(V) and the ice beverage(I) compared with compound the mix method(M) did not change significantly.The core temperature of before the precooling and after the precooling each conditions had no significant difference. The core temperature of the mix method(M) at the core of the temperature and the control(CONT, C) has a significant increase(P≤0.05) in comparison, and the cooling vest(V) and the ice beverage(I) compared with no difference.Before the precooling and after the precooling, the surface temperature of the ice beverage(I) and the mix method(M) and the cooling vest(V) comparison with the control(CONT, C) has a very significant increase(P≤0.01), the surface temperature of the cooling vest(V) in comparison with the control(CONT, C) is not differences. The surface temperature the ice beverage(I) and the mix method(M) is not in comparison with differences. After exercise, the surface temperature of the ice beverage(I) and the control(CONT, C) in comparison in the cooling vest(V) has a very significant increase(P≤0.01), the surface temperature of the ice beverage(I) has a significant increase(P≤0.05) in comparison with the mix method(M), the surface temperature of the control(CONT, C), the cooling vest(V) and the mix method(M) had no significant difference between each others.The RPE of before precooling and after precooling between conditions were no significant difference. After exercise of movement, the RPE of the mix method(M) in comparison with the control(CONT, C) had significantly lower(P≤0.05), the RPE of the cooling vest(V) and the ice beverage(I) in comparison with the control(CONT, C) there was no significant change. The RPB of before precooling and after precooling and after exercise each conditions were no significant difference. The rating of thermal sensation of before precooling and after precooling, after exercise in each conditions there was no significant difference.The blood lactic concentration of before the precooling and after the precooling of the ice beverage(I) and the mix method(M) had significantly lower(P≤0.05) in comparison with the control(CONT, C), The blood lactic concentration of the cooling vest(V) and the control(CONT, C), there was no significant difference in comparison with the mix method(M) and the ice beverage(I) and the cooling vest(V). After exercise the blood lactic concentration of each ones were no significant difference. The ratio of blood lactic concentration of the control(CONT, C), the cooling vest(V), the ice beverage(I) and the mix method(M) had no significant changes. 4、ConclusionIn hot/humidity condition, precooling measures has a promoting effect on the sub-maximal exercise of exhaustion exercise.The result may be contributed by precooling measures which could improve the exercise performance and maintain the stability of functional status of sports. Especially the mix method precooling, compared with cooling vest precooling and ice beverage cooling, can make prominent cooling effect. |
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