Background and Aim: Aging and the progressive effects of sarcopenia on muscle tissue, coupled with its synergy with obesity, highlight the increasing role of myostatin as a key factor in muscle atrophy and inter-tissue interactions. Physical exercise may influence these pathways. This study aimed to evaluate the impact of eight weeks of resistance training and high-intensity interval training (HIIT) on the strength of the lower limb muscles and myostatin levels in the visceral fat, soleus muscle, and serum of obese, aged male rats.
Methods: This experimental study involved 40 male Wistar rats (mean age: 15 months, weight: 320–350 grams). Ten rats were designated as the control group, while the remaining 30 underwent a high-fat diet for 12 weeks to induce obesity. Obese rats, with a Lee Index greater than 310, were divided into three groups: obese control, HIIT, and resistance training. The training regimen lasted eight weeks with three weekly sessions. The resistance training group performed exercises with weights corresponding to 25%, 50%, 75%, and 100% of body weight on a ladder. The HIIT group performed treadmill intervals at 85% (high intensity) and 50% (low intensity) of maximum speed in 2-minute intervals. Forty-eight hours after the final training session, tissue samples from the soleus muscle, serum, and visceral fat were collected.
Results: Significant differences in myostatin protein levels in the soleus muscle, visceral fat, and serum were observed between the control and exercise groups (P<0.05). Post-hoc analysis revealed that myostatin levels in the obese control group were significantly higher than those in the exercise and non-obese control groups across all measured tissues (P<0.05). While myostatin levels were lower in the resistance training group compared to the HIIT group, this difference was not statistically significant. Both training modalities reduced myostatin levels relative to the obese control group, although the reduction was not sufficient to bring levels closer to those of the non-obese control group.
Conclusion: Both resistance training and high-intensity interval training, through distinct mechanical and metabolic stressors, significantly reduced myostatin expression in various tissues. These findings suggest that physical exercise, regardless of modality, represents an effective approach to mitigate the rate of muscle atrophy associated with aging and sarcopenic obesity.