Reversal of metabolic adaptations induced by physical training after two weeks of physical detraining.

The present study aimed to evaluate the effect of two weeks of physical detraining (PD) on energy balance components, white adipose tissue (WAT) metabolism, body weight (BW) and adiposity. Male C57BL/6J mice were assigned into groups sedentary (S, n = 20) and trained (T, n = 18). Physical training (PT) consisted of two 1.5 h daily sessions of swimming, 5 times/week for 4 weeks. After the PT, some of the S (S4, n = 10) and T (T4, n = 8) animals were sacrificed, and the others were kept sedentary (S6, n = 10) or detrained for two weeks (D, n = 10). After PT, the T group showed lower BW compared with S group, but PD reversed this response. The BW gains were 4%, 3% and 6.3% in S, S6 and D groups, respectively, however the T group decreased by 1.7%. T4 and D groups showed lower visceral fat depots and larger heart and left ventricle weights compared with S4 and S6 groups. Food intake, oxygen consumption at rest and fasting-induced weight loss were higher in T4 group compared with S4, and this was reversed by PD. Serum concentration of insulin, the activity of enzyme FAS and mean blood pressure did not differ among groups, but the concentration of leptin and resting heart rate were lower in T4 and D groups compared with S4 and S6 groups. T4 group increased lipolytic activity stimulated by isoproterenol and citrate synthase activity, which were reversed by PD. In conclusion, PD reversed the components of energy balance by reducing food intake and resting metabolism, and impaired WAT lipolytic activity, but not lipogenic activity. These changes resulted in remodeling of BW, but not adiposity.