Effect Of High-Intensity Interval Training/Moderate-Intensity Continuous Training And Detraining On Fat Accumulation In Rats By High-Fat Diet

Objective:Compare the effect of 10-week High Intensity Interval Training（HIIT）and Moderate Intensity Continuous Training（MICT）on improving body fat,liver fat and blood fat,further observe the maintenance degree of these improvement effects after 6-weeks detraining,and at the histological anatomy level,observe the effect of MICT/HIIT and detraining on the adipocyte area and quantity.From the perspective of training and detraining,it provides more abundant evidence for exercise improve obesity and fatty liver caused by high-fat diet.Methods:Fifty-four female SD rats aged 7 weeks were randomly divided into high-fat diet high intensity interval training group（HIIT）,moderate intensity continuous training group（MICT）and without exercise group（CON）after 8-weeks high-fat feeding,with 18 rats in each group.The total distance of HIIT and MICT were equal.And rats exercise on treadmill until finish 10-week training（5 days per week）,MICT at a running speed equal to 50%～70%VO_2peakintensity for 45 minutes,HIIT at high intensity(85%～100%VO_2peak)for 1 minute,and lower intensity(50%～70%VO_2peak)exercises for 2 minutes.CON group did not exercise intervention.After 10 weeks,9 rats in each group were randomly selected to be killed,and the other 9 rats detraining and continued to eat high-fat diet for 6 weeks.The body weight and the inguinal/periuterine fat of rats in each group were measured;Tissue sectioning HE staining was used to observe the area and quantity of inguinal/periuterine adipocyte aera;Oil red O staining was used to observe liver fat content;Elisa tested the blood lipid content.The body weight blood lipids（TG,TC,HDL-C,LDL-C）,liver tissue oil red O staining gray value,inguinal/periuterine fat volume,adipocyte area and number of rats in each group after 10-weeks training and6-weeks detraining were compared by Two-way ANOVA analyse,with"group"and"detraining"as the main factors,The LSD method performs multiple comparisons after the fact.Results:（1）The effect of MICT/HIIT and detraining on body weightAfter 10-week training and 6-week detraining,the main effect of"training"and"detraining"of rats’body weight in each group was very significant（p<0.01）,the two factors have no interaction（p>0.05）.The weight of rats in the HIIT and MICT groups was significantly lower than that in the CON group（p<0.01）,HIIT and MICT have no significant difference;After 6-week detraining period,the weight of the three groups increased significantly,and there was no difference in the growth rate among the groups.（2）Effects of MICT/HIIT and detraining on body fat weightAfter 10-week training and 6-week detraining,the main effect of"training"and"detraining"on the weight of inguinal/periuterine fat of rats in each group were significant（p<0.01）,and the interaction effect was significant（p<0.05）.After 10-week training,the weight of inguinal/periuterine fat in the quiet control group were higher than that in the two exercise groups（p<0.05）,but there was no significant difference in the weight of inguinal/periuterine fat between the two exercise groups;After 6-week detraining,the weight of inguinal/periuterine fat in the three groups increased significantly,but the increase of the weight of inguinal/periuterine fat in HIIT group was significantly lower than that in MICT and CON group（p<0.05）.The increase of the weight of inguinal fat in MICT group was not significantly different from that in CON group,and the increase of the weight of periuterine fat in MICT group was significantly lower than that in CON group（p<0.05）.（3）Effects of MICT/HIIT and detraining on the area of adipocytes（1）After 10-week training and 6-week detraining,the main effect of"training"and"detraining"on the area of inguinal adipocytes of rats in each group were significant（p<0.01）,and the interaction effect was significant（p<0.01）.After 10-week training,the area of inguinal adipocytes in the two exercise groups was significantly lower than that in the quiet control group（p<0.05）,and there was no significant difference between the two exercise groups;After 6-week detraining period,there was no significant increase in the area of inguinal adipocytes in the HIIT group（p>0.05）,but significant increase in the MICT and CON groups（p<0.01）.The increase in the HIIT group was significantly lower than that in the MICT and CON groups,and the increase in the MICT group was significantly lower than that in the CON group（p<0.05）.（2）After 10-week training and 6-week detraining,the main effect of"training"and"detraining"on the area of periuterine fat cells of rats in each group were significant（p<0.01）,and the interaction effect was significant（p<0.05）.It was found that after 10-week training,the area of periuterine fat cells in the two exercise groups was significantly lower than that the quiet control group（p<0.01）,but there was no significant difference between the two exercise groups（p>0.05）;After 6-week detraining,the area of periuterine adipocytes in the three groups increased significantly（p<0.01）,but the increase in HIIT group was significantly lower than that in MICT group and CON group（p<0.01）,and the increase in MICT group was significantly lower than that in CON group（p<0.05）.（4）Effects of MICT/HIIT and detraining on liver fatAfter 10-week training and 6-weeks detraining,the main effect of"group"and"detraining"of liver tissue oil red O staining gray value of rats in each group was very significant（p<0.01）,and there was no interaction effect between the two factors（p>0.05）.It was found that the HIIT and MICT group’s liver tissue oil red O staining gray value was significantly lower than the CON group（p<0.05）,and there was no significant difference between the two exercise groups;After 6-week detraining,the gray value of oil red O staining in liver tissue of the three groups increase significantly,and the increase amplitude of each group was not different.there was no statistically significant increase in each group.（5）Effects of MICT/HIIT and detraining on blood lipidsAfter 10-week training and 6-week detraining,the"training"effect on serum TG and LDL-C content of rats in each group was very significant（p<0.01）,while the"detraining"effect was not significant（p>0.05）,and there was no interaction effect between the two factors（p>0.05）.The levels of TG and LDL-C in HIIT and MICT groups were significantly lower than those in CON group（p<0.05）,and there was no significant difference between the two exercise groups;After 6-week detraining period,there was no significant increase in TG and LDL-C content in the three groups.Conclusion:（1）Both HIIT and MICT can inhibit the accumulation of body fat caused by high fat diet,due to inhibiting adipocyte volume increase;the effect of HIIT on inhibiting body fat accumulation was better than that of MICT after 6-week detraining.（2）Both HIIT and MICT can inhibit the accumulation of liver fat and blood TG and LDL-C caused by high fat diet,and can still maintain the post exercise effect after 6-weeks detraining.