Effects And Its Mechanism Of High-Intensity Training And Moderate-Intensity Continuous Training On Body Composition In Overweight Young Female

Objective:High intensity interval training is a recently popular exercise mode,which is widely used in exercise weight loss because of its difference from traditional medium and low intensity continuous training with low power and long consumption time.This study intends to optimize some free hand movements with high compliance,simplicity and ability to achieve the target heart rate,use two different regimens of high-intensity interval training（HIIT）and moderate-intensity continuous training（MICT）to carry out 10-week exercise intervention for overweight young women,compare and analyze the training effects of the two exercise methods from the perspective of body composition,blood lipid metabolism and inflammation,provide more exercise programs for overweight/obese,sedentary and physically inactive people,and provide support for exploring new exercise forms under the condition of home exercise and limited venue devices.Methods:A total of 50 overweight young women were enrolled.After screening,30 effective subjects were determined and randomly divided into two groups,that is,HIIT and MICT group,with 15 subjects in each group.The mean height of the subjects was（164±4.32）cm;the mean age was（22±2.49）years.The 2 groups were given a 10-week training intervention,3 times/week,45 minutes each time,and the main training time was 30 minutes.The experimental protocol used a combination of free-hand actions,with every sixth action as one group,and each action lasted 30seconds.After 10 minutes of warm-up activity,the HIIT group performed training at90%VO₂max intensity,rested for 10 seconds after each action,and intermittently for1 minute,completing a total of 6 groups;MICT performed continuous training at 60%VO₂max intensity,10 groups,for a total of 30 minutes.At the end of the training,groups were stretched and relaxed collectively for 5 minutes.Before and after the experimental intervention,the height and weight of the subjects were measured using a height and weight meter;the neck circumference,waist circumference,hip circumference,and thigh circumference were measured using a flexible ruler,and the height and body mass index（BMI）was calculated:body mass（kg）/height²（m²）;the waist-to-hip circumference ratio was calculated;the skinfold thickness of the upper arm,back,and abdomen was measured using a skinfold forceps;and the body composition was measured using an Inbody 570 body composition tester.Using the Astand-Ryhnuiy indirect test method,subjects were tested for VO₂max before and after the intervention using a power bicycle,heart rate watch,and stopwatch.Subjects’quiet heart rate and blood pressure in the morning before and after the test intervention.Serum total cholesterol（TC）,triglyceride（TG）,low-density lipoprotein cholesterol（LDL-C）and high-density lipoprotein cholesterol（HDL-C）blood lipids were measured using serum lipid kits;inflammatory factors such as C-reactive protein（CRP）,tumor necrosis factor-α（TNF-α）,and interleukin-6（IL-6）were measured by ELISA.There were subjects who withdrew halfway and 25 who finally completed the experiment（12 in the HIIT group and 13 in the MICT group）.Results:（1）After training intervention,the body weight,WHR,BMI and body fat percentage of the HIIT group and the MICT group showed a downward trend,with significant differences compared with those before training（P<0.01,P<0.01,P<0.01,P<0.01）;compared with MICT group,the change value of waist-to-hip ratio in HIIT group was relatively higher,but there was no significant difference.Body weight and BMI reduction values were significantly increased（P<0.05,P<0.05）,body fat rate changes were similar to BMI changes,and body fat rate reduction values were significantly different compared with the MICT group（P<0.05）.After training intervention,the waist circumference,hip circumference and thigh circumference of the HIIT group and the MICT group showed a downward trend,with significant differences compared with those before training（P<0.01,P<0.01,P<0.01）;although the neck circumference of the HIIT group and the MICT group showed a downward trend compared with that before training,there were no significant changes.Compared with the MICT group,the change values of waist circumference and thigh circumference in the HIIT group were significantly different（P<0.05,P<0.05）,and although the change values of hip circumference and neck circumference were reduced,there was no significant difference.After training intervention,the abdominal skinfold thickness of the HIIT group and the MICT group showed a downward trend,with significant difference compared with that before training（P<0.01,P<0.05）;the back skinfold thickness showed a downward trend,with significant difference only in HIIT group compared with that before training（P<0.05）;the change of upper arm skinfold thickness was similar to that of back skinfold thickness,with significant difference only in HIIT group compared with that before training（P<0.01）.Compared with the MICT group,the change values of abdominal skinfold thickness were significantly different（P<0.01）,and although the change values of back and upper arm skinfold thickness in the MICT group were lower than those in the HIIT group,there was no significant difference.（2）After training intervention,the skeletal muscle of the HIIT group and the MICT group showed an increasing trend,with significant difference only in HIIT group compared with that before training（P<0.01）;the body fat weight showed a decreasing trend,with significant difference between the two groups compared with that before training（P<0.01,P<0.01）;the visceral fat grade and obesity showed a decreasing trend in both groups compared with those before training,with significant difference（P<0.01,P<0.01,P<0.01,P<0.01）.Compared with the MICT group,there were significant differences in skeletal muscle,body fat weight,visceral fat grade,and obesity change values in the HIIT group（P<0.01,P<0.05,P<0.05,P<0.05）.（3）After training intervention,the quiet heart rate of the HIIT group and the MICT group showed a downward trend,with significant differences compared with that before training（P<0.01,P<0.01）;VO₂max showed an increasing trend,with significant differences（P<0.01,P<0.05）;compared with MICT group,VO₂max of HIIT group increased significantly,with significant differences（P<0.01）;compared with that before training,MICT systolic blood pressure decreased significantly compared with that before training（P<0.01）,diastolic blood pressure changes in the two groups were close to the same,with significant decreases compared with that before training（P<0.01,P<0.01）;basal metabolic rate increased in both groups,with significant differences（P<0.01,P<0.01）,compared with MICT group,basal metabolic rate changes in HIIT group were significantly different（P<0.01）.（4）After training intervention,TG and TC of the HIIT group and the MICT group showed a downward trend,with significant difference only in HIIT group compared with those before training（P<0.01,P<0.05,P<0.01,P<0.01）;LDL-C showed a downward trend in both groups compared with those before training,with significant difference（P<0.01,P<0.05）,with significant decrease in HIIT group compared with MICT group（P<0.05）;HDL-C showed an increasing trend in both groups compared with those before training,but without significant difference.After training intervention,IL-6 and TNF-αin the HIIT group and the MICT group showed a downward trend,compared with those before training（P<0.01,P<0.01,P<0.01,P<0.01）,TNF-αchanges were significantly different（P<0.05）;compared with those before training,both groups showed a downward trend,and CRP in MICT group was significantly different（P<0.05）,CRP changes were not significantly different between the two groups.Conclusion:（1）10 weeks of HIIT and MICT training can improve the body shape and body composition of overweight young women,and HIIT is effective in controlling body fat and reducing body circumference under the same exercise duration.（2）10 weeks of both HIIT and MICT training reduced the quiet heart rate and blood pressure level of the subjects,increased the basal metabolic rate of the body,and improved cardiopulmonary function.（3）10-week HIIT and MICT training may improve blood lipid metabolism in the human body by regulating the contents of TG,TC,LDL-C,and HDL-C in the body;reduce the levels of IL-6,TNF-α,and CRP in the body,and reduce the body’s inflammatory response.