Background/Objectives: The combined effects of aerobic exercise and normobaric hyperoxia exposure on skeletal muscle in diabetes mellitus (DM) remain unclear. This study investigated whether their combination influences skeletal muscle capillary and mitochondrial function in diabetic rats. Methods: Seven-week-old male Wistar rats were randomly assigned to the following five groups: control (CON), DM, DM with aerobic exercise (DMEx), DM with aerobic exercise under 30% oxygen exposure (DMEx30), and DM with aerobic exercise under 50% oxygen exposure (DMEx50). Aerobic exercise and normobaric hyperoxia exposure were performed simultaneously in the DMEx30 and DMEx50 groups. Results: Combined aerobic exercise and normobaric hyperoxia significantly improved both capillary density and succinate dehydrogenase (SDH) activity in the soleus muscle, which is predominantly composed of slow-twitch fibers, in diabetic rats. In contrast, the effects were more limited in predominantly fast-twitch muscles, including the extensor digitorum longus and plantaris muscles. Conclusions: Combined aerobic exercise and normobaric hyperoxia may induce beneficial skeletal muscle adaptations in diabetic rats, with more pronounced effects in the predominantly slow-twitch soleus muscle than in predominantly fast-twitch muscles. These findings suggest that muscle fiber-type composition may influence responsiveness to this intervention. This combined approach may contribute to the development of novel exercise-based interventions for DM.
Sugimoto et al. (Mon,) studied this question.