West J B, Boyer S J, Graber D J, Hackett P H, Maret K H, Milledge J S, Peters R M, Pizzo C J, Samaja M, Sarnquist F H
J Appl Physiol Respir Environ Exerc Physiol. 1983 Sep;55(3):688-98. doi: 10.1152/jappl.1983.55.3.688.
Maximal exercise at extreme altitudes was studied during the course of the American Medical Research Expedition to Everest. Measurements were carried out at sea level [inspired O2 partial pressure (PO2) 147 Torr], 6,300 m during air breathing (inspired PO2 64 Torr), 6,300 m during 16% O2 breathing (inspired PO2 49 Torr), and 6,300 m during 14% O2 breathing (inspired PO2 43 Torr). The last PO2 is equivalent to that on the summit of Mt. Everest. All the 6,300 m studies were carried out in a warm well-equipped laboratory on well-acclimatized subjects. Maximal O2 uptake fell dramatically as the inspired PO2 was reduced to very low levels. However, two subjects were able to reach an O2 uptake of 1 l/min at the lowest inspired PO2. Arterial O2 saturations fell markedly and alveolar-arterial PO2 differences increased as the work rate was raised at high altitude, indicating diffusion limitation of O2 transfer. Maximal exercise ventilations exceeded 200 l/min at 6,300 m during air breathing but fell considerably at the lowest values of inspired PO2. Alveolar CO2 partial pressure was reduced to 7-8 Torr in one subject at the lowest inspired PO2, and the same value was obtained from alveolar gas samples taken by him at rest on the summit. The results help to explain how man can reach the highest point on earth while breathing ambient air.
在美国医学研究队攀登珠穆朗玛峰的过程中，对极端海拔高度下的最大运动进行了研究。在海平面（吸入氧分压（PO₂）147托）、海拔6300米空气呼吸时（吸入PO₂ 64托）、海拔6300米吸入16%氧气呼吸时（吸入PO₂ 49托）以及海拔6300米吸入14%氧气呼吸时（吸入PO₂ 43托）进行了测量。最后一个PO₂值相当于珠穆朗玛峰峰顶的氧分压。所有在海拔6300米进行的研究都是在一个温暖且设备齐全的实验室中，对适应良好的受试者进行的。随着吸入PO₂降至极低水平，最大摄氧量急剧下降。然而，两名受试者在最低吸入PO₂时能够达到1升/分钟的摄氧量。在高海拔地区，随着工作强度增加，动脉血氧饱和度显著下降，肺泡 - 动脉血氧分压差增大，这表明存在氧气转移的弥散限制。在海拔6300米空气呼吸时，最大运动通气量超过200升/分钟，但在最低吸入PO₂值时大幅下降。在最低吸入PO₂时，一名受试者的肺泡二氧化碳分压降至7 - 8托，这与他在峰顶休息时采集的肺泡气体样本所得到的值相同。这些结果有助于解释人类在呼吸周围空气的情况下如何能够到达地球的最高点。
