Carrithers John A, Carroll Chad C, Coker Robert H, Sullivan Dennis H, Trappe Todd A
Nutrition, Metabolism, and Exercise Laboratory, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
Aviat Space Environ Med. 2007 May;78(5):457-62.
Exercise countermeasures for long duration space crews incorporate aerobic and resistance exercise (i.e., concurrent training). Microgravity simulation studies show that resistance exercise alone can be completely effective at preventing muscle loss, yet crews return from missions with reduced muscle mass and function. Some Earth-based studies show human skeletal muscle size and strength increases typically noted with resistance training are blunted when aerobic and resistance training are performed concurrently. The purpose of this study was to determine if the addition of aerobic exercise prior to performing resistance exercise blunts the acute anabolic response to resistance exercise.
Myofibrillar protein synthesis rates were determined in 12 individuals (6 men, 6 women, 26 +/- 2 yr) by measuring the incorporation of [2H5]phenylalanine into vastus lateralis muscle protein following resistance exercise (4 sets of 10 repetitions of both leg press and leg extension) and following resistance exercise that had been preceded by 90 min of strenuous aerobic cycling exercise.
Myofibrillar protein synthesis following resistance exercise (0.092 +/- 0.006% x h(-1)) was not suppressed (p > 0.05) compared with following concurrent exercise (0.100 +/- 0.007% x h(-1)).
It appears the anabolic response to resistance exercise cannot explain the attenuated muscle mass and strength gains imposed by chronic concurrent aerobic and resistance training, nor the response of space crews to in-flight concurrent countermeasures. These findings have important implications for future optimization of the concurrent aerobic and resistance exercise countermeasures for long duration space crews.
针对长期太空任务乘员的运动对策包括有氧运动和抗阻运动（即联合训练）。微重力模拟研究表明，单独进行抗阻运动在预防肌肉流失方面可能完全有效，但乘员执行任务返回后肌肉量和功能仍会下降。一些地面研究表明，当同时进行有氧运动和抗阻训练时，通常在抗阻训练中观察到的人类骨骼肌大小和力量增加会受到抑制。本研究的目的是确定在进行抗阻运动之前增加有氧运动是否会减弱对抗阻运动的急性合成代谢反应。
通过测量[2H5]苯丙氨酸掺入股外侧肌蛋白质的情况，在12名个体（6名男性，6名女性，26±2岁）中测定肌原纤维蛋白合成率，分别在进行抗阻运动（腿举和腿伸展各4组，每组10次重复）后以及在进行90分钟剧烈有氧骑行运动后再进行抗阻运动后进行测量。
与联合运动后（0.100±0.007%×h-1）相比，抗阻运动后的肌原纤维蛋白合成（0.092±0.006%×h-1）未受到抑制（p>0.05）。
看来，对抗阻运动的合成代谢反应无法解释长期同时进行有氧运动和抗阻训练所导致的肌肉量和力量增加减弱的情况，也无法解释太空乘员对飞行中联合对策的反应。这些发现对于未来优化长期太空任务乘员的有氧运动和抗阻运动联合对策具有重要意义。
