Pulmonary Division and Center for Human Integrative Physiology, University of Zurich , Zurich , Switzerland.
J Appl Physiol (1985). 2017 Dec 1;123(6):1657-1670. doi: 10.1152/japplphysiol.00186.2017. Epub 2017 Aug 3.
Exercise performance is determined by oxygen supply to working muscles and vital organs. In healthy individuals, exercise performance is limited in the hypoxic environment at altitude, when oxygen delivery is diminished due to the reduced alveolar and arterial oxygen partial pressures. In patients with pulmonary hypertension (PH), exercise performance is already reduced near sea level due to impairments of the pulmonary circulation and gas exchange, and, presumably, these limitations are more pronounced at altitude. In studies performed near sea level in healthy subjects, as well as in patients with PH, maximal performance during progressive ramp exercise and endurance of submaximal constant-load exercise were substantially enhanced by breathing oxygen-enriched air. Both in healthy individuals and in PH patients, these improvements were mediated by a better arterial, muscular, and cerebral oxygenation, along with a reduced sympathetic excitation, as suggested by the reduced heart rate and alveolar ventilation at submaximal isoloads, and an improved pulmonary gas exchange efficiency, especially in patients with PH. In summary, in healthy individuals and in patients with PH, alterations in the inspiratory Po by exposure to hypobaric hypoxia or normobaric hyperoxia reduce or enhance exercise performance, respectively, by modifying oxygen delivery to the muscles and the brain, by effects on cardiovascular and respiratory control, and by alterations in pulmonary gas exchange. The understanding of these physiological mechanisms helps in counselling individuals planning altitude or air travel and prescribing oxygen therapy to patients with PH.
运动表现取决于向工作肌肉和重要器官输送的氧气。在健康个体中，由于肺泡和动脉氧分压降低导致氧输送减少，在高原的低氧环境中，运动表现会受到限制。在肺动脉高压（PH）患者中，由于肺循环和气体交换受损，即使在海平面，运动表现也已经降低，而且这些限制在高原可能更为明显。在海平面进行的健康受试者和 PH 患者的研究中，通过吸入富氧空气，可显著增强递增斜坡运动中的最大性能和亚最大恒负荷运动的耐力。在健康个体和 PH 患者中，这些改善是通过更好的动脉、肌肉和脑氧合以及减少交感神经兴奋来介导的，这可以从亚最大等负荷时的心率和肺泡通气减少以及肺气体交换效率改善看出，特别是在 PH 患者中。总之，在健康个体和 PH 患者中，通过暴露于低压缺氧或常压高氧改变吸气 Po2 分别会降低或增强运动表现，其机制为通过改变肌肉和大脑的氧输送、对心血管和呼吸控制的影响以及肺气体交换的改变来实现。对这些生理机制的理解有助于为计划前往高原或航空旅行的个体提供建议，并为 PH 患者开具氧疗处方。
