Impact to short-term high intensity intermittent training on different storages of body fat, leptin and soluble leptin receptor levels in physically active non-obese men: A pilot investigation

Summary Background & aims Studies have postulated High Intensity Intermittent Training (HIIT) as a superior strategy to reduce body fat. The purpose of this study was to compare the effects HIIT and steady-state training (SST) on body composition, leptin, soluble leptin receptor (sOB-R) levels, and hunger perception in physically active non-obese men. Methods Twenty men performed five weeks of HIIT (5 km – 1 min running at 100% speed correspondent to VȩO2peak – v VȩO2peak – interspersed with 1-min passive recovery; n = 10) or SST (5 km at 70% of vVȩO2peak continuously; n = 10) three times a week. Body composition, and hunger perception were assessed at pre- and post-training and were compared by a two-way analysis (group and training period) with repeated measures in the second factor. A fasting time-course (baseline, 24 h, and 48 h after an experimental session of exercise) of leptin and sOB-R levels were measured at pre- and post-five weeks of training and assessed by a three-way analysis (group, period and time of measurement) with repeated measures in the second and third factors. Results There was no effect on body composition and hunger perception. Leptin was reduced in both groups, while sOB-R was increased post-five weeks of training in HIIT but not in the SST. Conclusions Although both training groups exerted alterations in leptin levels, only HIIT was able increased sOB-R levels, this suggest a superior impact on central responses in physically active non-obese men.