It has been observed that there is an inverse relationship between fiber size and oxidative capacity due to oxygen, ADP, and ATP diffusion limitations. We aimed to see if regular endurance exercise alongside a hypertrophic stimulus would lead to compromised adaptations to both, particularly in older animals. Here we investigated the effects of combining overload with regular endurance exercise in young (12 months) and old (26 months) male mice. The plantaris muscles of these mice were overloaded through denervation of synergists to induce hypertrophy and the mice ran on a treadmill for 30 min per day for 6 weeks. The hypertrophic response to overload was not blunted by endurance exercise, and the increase in fatigue resistance with endurance exercise was not reduced by overload. Old mice demonstrated less hypertrophy than young mice, which was associated with impaired angiogenesis and a reduction in specific tension. The data of this study suggest that combining endurance exercise and overload induces the benefits of both types of exercise without compromising adaptations to either. Additionally, the attenuated hypertrophic response to overload in old animals may be due to a diminished capacity for capillary growth.

据观察，由于氧、ADP 和 ATP 扩散限制，纤维尺寸和氧化能力之间存在反比关系。我们的目的是看看定期的耐力运动和肥大刺激是否会导致对两者的适应受损，特别是对于老年动物。在这里，我们研究了将超负荷与定期耐力运动相结合对年轻（12 个月）和年老（26 个月）雄性小鼠的影响。通过增效剂的去神经诱导小鼠肥大，这些小鼠的跖肌超负荷，小鼠每天在跑步机上跑步 30 分钟，持续 6 周。耐力运动不会减弱对超负荷的肥大反应，耐力运动带来的疲劳抵抗力的增加也不会因超负荷而减弱。年老小鼠的肥大程度低于年轻小鼠，这与血管生成受损和比张力降低有关。这项研究的数据表明，将耐力运动和超负荷结合起来可以带来两种运动的益处，而不影响对任何一种运动的适应。此外，老年动物对超负荷的肥大反应减弱可能是由于毛细血管生长能力减弱所致。