Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia.
Department of Medicine, University of Udine, Udine, Italy.
Am J Physiol Regul Integr Comp Physiol. 2021 Dec 1;321(6):R813-R822. doi: 10.1152/ajpregu.00053.2021. Epub 2021 Sep 29.
This retrospective study was designed to analyze the interindividual variability in the responses of different variables characterizing the skeletal muscle oxidative function to normoxic (N-BR) and hypoxic (H-BR) bed rests and to a hypoxic ambulatory confinement (H-AMB) of 10 and 21 days. We also assessed whether and how the addition of hypoxia to bed rest might influence the heterogeneity of the responses. In vivo measurements of O uptake and muscle fractional O extraction were carried out during an incremental one-leg knee-extension exercise. Mitochondrial respiration was assessed in permeabilized muscle fibers. A total of 17 subjects were included in this analysis. This analysis revealed a similar variability among subjects in the alterations induced by N-BR and H-BR both in peak O uptake (SD: 4.1% and 3.3% after 10 days; 4.5% and 8.1% after 21 days, respectively) and peak muscle fractional O extraction (SD: 5.9% and 7.3% after 10 days; 6.5% and 7.3% after 21 days), independently from the duration of the exposure. The individual changes measured in these variables were significantly related ( = 0.66, = 0.004 after N-BR; = 0.61, = 0.009 after H-BR). Mitochondrial respiration showed a large variability of response after both N-BR (SD: 25.0% and 15.7% after 10 and 21 days) and H-BR (SD: 13.0% and 19.8% after 10 and 21 days); no correlation was found between N-BR and H-BR changes. When added to bed rest, hypoxia altered the individual adaptations within the mitochondria but not those intrinsic to the muscle oxidative function in vivo, both after the short- and medium-term exposures.
这项回顾性研究旨在分析不同变量特征的个体间变异性，这些变量描述了骨骼肌氧化功能对常氧（N-BR）和低氧（H-BR）卧床休息以及 10 天和 21 天低氧步行限制（H-AMB）的反应。我们还评估了向卧床休息中添加低氧是否会影响反应的异质性。在递增单腿膝关节伸展运动期间进行了 O 摄取和肌肉分数 O 提取的体内测量。在通透的肌肉纤维中评估了线粒体呼吸。共有 17 名受试者参与了这项分析。这项分析表明，在 N-BR 和 H-BR 引起的峰值 O 摄取变化（10 天后的 SD：分别为 4.1%和 3.3%；21 天后的 SD：分别为 4.5%和 8.1%）和峰值肌肉分数 O 提取变化（10 天后的 SD：分别为 5.9%和 7.3%；21 天后的 SD：分别为 6.5%和 7.3%）中，受试者之间的变异性相似，独立于暴露时间。这些变量中测量的个体变化明显相关（N-BR 后为 0.66， = 0.004；H-BR 后为 0.61， = 0.009）。N-BR（10 天和 21 天后的 SD：分别为 25.0%和 15.7%；H-BR：分别为 13.0%和 19.8%）和 H-BR 后，线粒体呼吸显示出较大的反应变异性；在 N-BR 和 H-BR 之间没有发现变化的相关性。当添加到卧床休息中时，低氧改变了线粒体中的个体适应，但没有改变体内肌肉氧化功能的内在适应，无论是在短期还是中期暴露后。
