Hoppeler H, Desplanches D
Department of Anatomy, University of Bern, Switzerland.
Int J Sports Med. 1992 Oct;13 Suppl 1:S166-8. doi: 10.1055/s-2007-1024628.
The effects of prolonged severe hypoxia on human performance capacity and muscle structure and function have recently been studied during real and simulated ascents to Mt. Everest. The results of several independent research teams, using different techniques, are broadly compatible. It is found that body and muscle mass is significantly reduced after exposure to hypoxia. As a consequence, muscle fiber size is also reduced. The capillary density of muscle tissue is increased, not because of capillary neoformation, but because of the reduction in muscle fiber size. The activities of enzymes of the oxidative pathways are decreased in skeletal muscle tissue. A loss of mitochondria is the structural evidence of the diminished potential for muscle oxidative metabolism. In contrast to these results, recent experimentations with hypoxia in human exercise settings have demonstrated that if hypoxia is only present during a limited daily period of an endurance training session, hypoxia has a different effect on muscle tissue. It is found that muscle fiber size, capillarity, myoglobin concentration and muscle oxidative capacity are all enhanced with training in hypoxia. These controversial findings raise questions regarding the nature of the adaptational mechanisms triggered by the different hypoxic stimuli to which subjects had been subjected and thus offer important new venues for further studies on the control of protein metabolism in muscle tissue.
最近在实际攀登和模拟攀登珠穆朗玛峰的过程中，研究了长期严重缺氧对人体运动能力以及肌肉结构和功能的影响。几个独立研究团队采用不同技术得出的结果大致相符。研究发现，暴露于缺氧环境后，身体和肌肉质量显著下降。因此，肌纤维大小也会减小。肌肉组织的毛细血管密度增加，这并非由于毛细血管新生，而是因为肌纤维大小减小。骨骼肌组织中氧化途径的酶活性降低。线粒体的丢失是肌肉氧化代谢潜力降低的结构证据。与这些结果相反，最近在人体运动环境中进行的缺氧实验表明，如果缺氧仅在耐力训练课程的有限每日时间段内出现，那么缺氧对肌肉组织会产生不同的影响。研究发现，通过在缺氧环境中训练，肌纤维大小、毛细血管密度、肌红蛋白浓度和肌肉氧化能力均会增强。这些相互矛盾的发现引发了关于不同缺氧刺激所触发的适应机制本质的问题，而受试者正是受到了这些刺激，因此为进一步研究肌肉组织中蛋白质代谢的控制提供了重要的新途径。
