Moore Alan D, Downs Meghan E, Lee Stuart M C, Feiveson Alan H, Knudsen Poul, Ploutz-Snyder Lori
Wyle Science, Technology & Engineering Group, Houston, Texas;
University of Houston, Houston, Texas;
J Appl Physiol (1985). 2014 Aug 1;117(3):231-8. doi: 10.1152/japplphysiol.01251.2013. Epub 2014 Jun 26.
This investigation was designed to measure aerobic capacity (V̇o2peak) during and after long-duration International Space Station (ISS) missions. Astronauts (9 males, 5 females: 49 ± 5 yr, 77.2 ± 15.1 kg, 40.6 ± 6.4 ml·kg(-1)·min(-1) [mean ± SD]) performed peak cycle tests ∼90 days before flight, 15 days after launch, every ∼30 days in-flight, and on recovery days 1 (R + 1), R + 10, and R + 30. Expired metabolic gas fractions, ventilation, and heart rate (HR) were measured. Data were analyzed using mixed-model linear regression. The main findings of this study were that V̇o2peak decreased early in-flight (∼17%) then gradually increased during flight but never returned to preflight levels. V̇o2peak was lower on R + 1 and R + 10 than preflight but recovered by R + 30. Peak HR was not different from preflight at any time during or following flight. A sustained decrease in V̇o2peak during and/or early postflight was not a universal finding in this study, since seven astronauts were able to attain their preflight V̇o2peak levels either at some time during flight or on R + 1. Four of these astronauts performed in-flight exercise at higher intensities compared with those who experienced a decline in V̇o2peak, and three had low aerobic capacities before flight. These data indicate that, while V̇o2peak may be difficult to maintain during long-duration ISS missions, aerobic deconditioning is not an inevitable consequence of long-duration spaceflight.
本研究旨在测量长期国际空间站（ISS）任务期间及之后的有氧能力（峰值摄氧量，V̇o2peak）。宇航员（9名男性，5名女性：年龄49±5岁，体重77.2±15.1千克，V̇o2peak为40.6±6.4毫升·千克⁻¹·分钟⁻¹[均值±标准差]）在飞行前约90天、发射后15天、飞行期间每隔约30天以及恢复日1（R + 1）、R + 10和R + 30进行峰值自行车测试。测量呼出代谢气体成分、通气量和心率（HR）。使用混合模型线性回归分析数据。本研究的主要发现是，V̇o2peak在飞行早期下降（约17%），然后在飞行期间逐渐增加，但从未恢复到飞行前水平。R + 1和R + 10时的V̇o2peak低于飞行前，但到R + 30时恢复。飞行期间及之后的任何时候，峰值心率与飞行前均无差异。在本研究中，飞行期间和/或飞行后早期V̇o2peak持续下降并非普遍现象，因为7名宇航员在飞行期间的某个时间或R + 1时能够达到其飞行前的V̇o2peak水平。与V̇o2peak下降的宇航员相比，其中4名宇航员在飞行中进行了更高强度的锻炼，另外3名在飞行前有氧能力较低。这些数据表明，虽然在长期的国际空间站任务期间可能难以维持V̇o2peak，但有氧能力下降并非长期太空飞行的必然结果。
