Efeitos do exercício aeróbio em diferentes momentos no ciclo claro-escuro sobre a composição corporal, desempenho físico e parâmetros de estresse oxidativo em ratos Wistar

Abstract

Physical training is recognized as a low-cost intervention, as well as being a safe and essential strategy in the prevention and treatment of diseases. These events involve behavioral and molecular adjustments of different metabolic pathways. Among these, the influence of physical training on the circadian rhythm, especially in the muscular and redox context, is still under-explored. In this perspective, the present study aimed

to investigate the effects of aerobic exercise performed at different phases of the light- dark cycle on body composition, physical performance, and parameters of oxidative

stress and antioxidant response in Wistar rats. Male rats were subjected to an aerobic training protocol on a treadmill during the light (day) or dark (night) period for seven weeks, and the effects were evaluated in different tissues and post-exercise times (1h, 24h, 48h, and 72h). Animals exercised at night showed higher physical performance, lower oxidative stress, and better antioxidant response, especially in the soleus muscle (p<0.01), which is abundant in oxidative fibers. Daytime training promoted increased oxidative stress, particularly in the gastrocnemius muscle (p<0.01), followed by a delayed increase in antioxidant activity (p<0.05) and protein synthesis, suggesting a compensatory adaptive response. In terms of body composition, aerobic exercise significantly reduced visceral fat, regardless of training time (p<0.0001), suggesting that lipolytic mechanisms are less sensitive to circadian modulation. In addition, specific differences in muscle mass were observed: the soleus responded positively to exercise at both times (p<0.01), (p<0.0001) respectively, while the gastrocnemius showed hypertrophy only during the daytime (p<0.05), and the quadriceps showed no significant changes (p>0.05). This evidence suggests that the time at which aerobic exercise is performed may have a specific effect on muscle and redox adaptations, reinforcing the role of the circadian rhythm in regulating metabolism and performance. Exercise during the active phase of the rodents (dark period) proved to be more effective in promoting functional and antioxidant benefits. Finally, the results highlight the importance of considering biological rhythms when designing physical training protocols in experimental models. Further investigation and evaluation of components related to the circadian cycle and redox signaling are suggested, which could be addressed in future research.