Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
J Appl Physiol (1985). 2013 Jun;114(11):1527-35. doi: 10.1152/japplphysiol.00883.2012. Epub 2013 Mar 21.
Oxidative function during exercise was evaluated in 11 young athletes with marked skeletal muscle hypertrophy induced by long-term resistance training (RTA; body mass 102.6 ± 7.3 kg, mean ± SD) and 11 controls (CTRL; body mass 77.8 ± 6.0 kg). Pulmonary O2 uptake (Vo2) and vastus lateralis muscle fractional O2 extraction (by near-infrared spectroscopy) were determined during an incremental cycle ergometer (CE) and one-leg knee-extension (KE) exercise. Mitochondrial respiration was evaluated ex vivo by high-resolution respirometry in permeabilized vastus lateralis fibers obtained by biopsy. Quadriceps femoris muscle cross-sectional area, volume (determined by magnetic resonance imaging), and strength were greater in RTA vs. CTRL (by ∼40%, ∼33%, and ∼20%, respectively). Vo2peak during CE was higher in RTA vs. CTRL (4.05 ± 0.64 vs. 3.56 ± 0.30 l/min); no difference between groups was observed during KE. The O2 cost of CE exercise was not different between groups. When divided per muscle mass (for CE) or quadriceps muscle mass (for KE), Vo2 peak was lower (by 15-20%) in RTA vs. CTRL. Vastus lateralis fractional O2 extraction was lower in RTA vs. CTRL at all work rates, during both CE and KE. RTA had higher ADP-stimulated mitochondrial respiration (56.7 ± 23.7 pmol O2·s(-1)·mg(-1) ww) vs. CTRL (35.7 ± 10.2 pmol O2·s(-1)·mg(-1) ww) and a tighter coupling of oxidative phosphorylation. In RTA, the greater muscle mass and maximal force and the enhanced mitochondrial respiration seem to compensate for the hypertrophy-induced impaired peripheral O2 diffusion. The net results are an enhanced whole body oxidative function at peak exercise and unchanged efficiency and O2 cost at submaximal exercise, despite a much greater body mass.
在 11 名长期抗阻训练导致骨骼肌显著肥大的年轻运动员（RTA；体重 102.6 ± 7.3kg，均值 ± SD）和 11 名对照组（CTRL；体重 77.8 ± 6.0kg）中评估了运动时的氧化功能。在递增式踏车（CE）和单腿伸膝（KE）运动期间，通过近红外光谱法测定肺 O2 摄取量（Vo2）和股外侧肌局部 O2 提取分数。通过活检获得的股外侧肌透化纤维，用高分辨率呼吸测定法评估了线粒体呼吸。与 CTRL 相比，RTA 的股四头肌横截面积、体积（通过磁共振成像确定）和力量更大（分别增加了约 40%、约 33%和约 20%）。与 CTRL 相比，RTA 的 CE 运动时 Vo2peak 更高（4.05 ± 0.64 vs. 3.56 ± 0.30 l/min）；在 KE 期间两组之间没有差异。CE 运动的 O2 消耗在两组之间没有差异。当按肌肉质量（CE）或股四头肌质量（KE）进行分组时，RTA 的 Vo2peak 比 CTRL 低（低 15-20%）。与 CTRL 相比，在 CE 和 KE 的所有工作率下，RTA 的股外侧肌局部 O2 提取分数均较低。RTA 的 ADP 刺激线粒体呼吸（56.7 ± 23.7 pmol O2·s(-1)·mg(-1) ww）比 CTRL 高（35.7 ± 10.2 pmol O2·s(-1)·mg(-1) ww），氧化磷酸化的耦合更紧密。在 RTA 中，更大的肌肉质量和最大力量以及增强的线粒体呼吸似乎补偿了肥大引起的外周 O2 扩散受损。尽管体重更大，但在峰值运动时全身氧化功能增强，亚最大运动时效率和 O2 消耗不变。
