| ObjectiveExercise is a popular means of weight loss.However,exercise-induced weight loss is often less than expected,and individual differences are significant.Some studies suggest that the magnitude of exercise-induced weight loss depends on the extent of compensatory reponse.The compensatory response manifests itself in numerous ways,and the final result of which is to maintain energy balance.Some studies show that the reduction of spontaneous physical activity after exercise is a manifestation of physical activity compensation,while another studies indicate that exercise does not lead to compensation,but rather increases spontaneous physical activity.At present,whether exercise will cause a decrease in spontaneous physical activity energy expenditure for compensation is still controversial,and whether there is a difference between different exercise mode and different weight categories is not clear.Therefore,this study examined the effects of 6-week aerobic and aerobic plus resistance exercise(two popular ways to lose weight)on spontaneous physical activity in adolescents with overweight or normal weight to explore whether exercise will result in reduced spontaneous physical activity,and whether exercise mode and BMI are important factor for exercise-induced spontaneous physical activity compensation,so as to provide help for exercise to lose weight.MethodsIn this study,47 freshman boys from Zhongshan polytechnic were recruited.Among them,17 were overweight and 30 were normal weight.The subjects were randomly divided into control group,aerobic exercise group,and aerobic plus resistance exercise group according to body weight category.The control participants were required to maintain their pre-intervention habitual physical activity levels.The exercise group took part in exercise training for 6 weeks(4 times a week for 60 minutes),badminton,jogging were applied for aerobic exercise section.The intensity was controlled at 60 to 75% of the maximum heart rate.The aerobic plus resistance exercise group took first aerobic exercise section for 30 minutes(same as aerobic exercise group)and then went on resistance section for another 30 minutes.The resistance movement is performed in 2 combinations at a time,8 actions for each combination,8-12 repetitions for each action,the combination was intermittent for 2 minutes and each action was intermittent for 1 minute.Body composition,resting metabolism and spontaneous physical activity were measuredbefore and after intervention.The body composition was tested by bio-impedance method,resting metabolism was examined by indirect calorimetry,and spontaneous physical activity was tested by triaxial accelerometer.The data was analyzed using SPSS 18.0,matched sample T test was used for intra-group comparison,independent sample T test was used for inter-group comparison,and multiple groups were compared using ANOVA.Results1.Intra-group comparison:(1)Comparison between control and exercise group:After the intervention body composition and resting metabolism were not changed in the control group;while the body weight and body fat% were decreased significantly(P <0.01)in the exercise group,and lean body mass and resting metabolism were not changed in the exercise group.In terms of spontaneous physical activity,there was no significant change between pre-test and post-test in the control group.However Total Activity Counts,Vector Magnitude Vounts and Moderate in the exercise group decreased significantly(P < 0.05),but there was no significant change in Sedentary Time and Light.(2)Comparison between control and exercise group according to body weight: For both adolescents with overweight and normal weight,there was no significant change in body composition and resting metabolism between pre-test and post-test in control group,In the exercise group,regardless of being overweight or normal weight,body weight and body fat% decreased significantly(P < 0.05),and there was no significant change in lean body mass and resting metabolism;in terms of spontaneous physical activity,there were no significant changes in the indexes of spontaneous physical activity in overweight individuals in both control group and exercise group.However,the Total Activity Counts,Moderate,Vector Magnitude Counts and Kcals decreased significantly(P < 0.05),and the Sedentary Time,Light remained unchanged in the normal weight individuals in the exercise group.(3)Comparison between the two exercise groups before and after exercise intervention: For body composition and resting metabolism,the body weight and body fat% of aerobic exercise group and aerobic plus resistance exercise group decreased significantly(P < 0.05),however there was no significant change in lean body mass and resting metabolism between pre-test and post-test;For the spontaneous physical activity,Total Activity Counts decreased significantly in the aerobic exercise group(P < 0.05),while the Kcals and Light were reduced significantly(P < 0.05)in the aerobic plus resistance exercise group,and there was no significant change in other indicators between the two groups.(4)Comparison between the two exercise groups according to body weight: For body composition and resting metabolism,the body weight of normal weightindividuals and body fat% of overweight individuals in both aerobic exercise group and aerobic plus resistance exercise group decreased significantly(P < 0.05).2.Inter-group comparison:(1)Comparison between the control group and the two exercise group: before intervention,there was no significant difference among control group,aerobic exercise group,and aerobic plus resistance exercise group.After intervention,the only difference among the three group was resting metabolism:compared with the control group and the aerobic exercise group,the aerobic plus resistance exercise group had higher levels of resting metabolism,but there was no difference between the aerobic exercise group and control group;In terms of spontaneous physical activity,there was no difference in both pre-test or post-test between the control group,aerobic exercise group,and aerobic plus exercise group.(2)Comparision between different body weight categories: no matter in pre-test or post-test,there was no difference in spontaneous physical activity between overweight and normal weight individuals.Conclusion1.The 6-week exercise not only had a significant weight-reducing effect,but also caused a spontaneous physical activity compensatory response,but there was no difference between aerobic exercise and aerobic plus resistance exercise in spontaneous physical activity.2.There was no difference in spontaneous physical activity between overweight and normal weight individuals.However,exercise causes spontaneous physical activity compensation in normal weight individuals,but no compensatory response was found in overweight individuals.3.The exercise-induced compensatory response does not compensate for the energy consumption caused by the exercise itself. |
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