The effects of HIIT/MICT on the inhibition of fat accumulation during training and detraining

Abstract Background: HIIT had at least comparable effect on inhibiting the increase of fat compared with MICT. However, few studies have been conducted to examine their effects of detraining on body fat with high-fat diet rats. This study aimed to compare the effects of 10-week high-intensity interval training (HIIT) and moderate intensity continuous training (MICT) as well as 6-week detraining on body fat in high-fat diet rats. Methods: After 8-week high-fat feeding, fifty-four rats were randomly assigned to six groups: 1)CON-T(n = 9): sedentary for 10 weeks (T10); 2)MICT-T(n = 9): 10-week MICT; 3)HIIT-T(n = 9): 10-week HIIT; 4)CON-D(n = 9):sedentary for 16 weeks (T16); 5)MICT-D(n = 9): 10-week MICT and 6-week training cessation; 6)HIIT-D(n = 9): 10-week HIIT and 6-week training cessation. The training cession performed 5 days/week. The subcutaneous (inguinal; SCAT), visceral (periuterine; VAT) adipose tissue and serum lipid profiles were analyzed by histological staining. ATGL expression in VAT was assessed by Western Blot at T10 and T16. Results: Ten-week HIIT and MICT inhibited the increase of SCAT, VAT and serum lipid levels compared with CON. After 6-week detraining, HIIT continued to inhibit the increase of adipose tissue mass whereas MICT at least maintained this inhibition induced by the training compared with CON. The inhibition primarily resulted from the adipocyte hypertrophy prevention. HIIT showed the most significant expression of ATGL after training and detraining. Conclusions: HIIT which had a comparable effect to MICT in preventing fat mass increase during training showed superior sustainability to MICT after detraining.