Weiss Edward P, Racette Susan B, Villareal Dennis T, Fontana Luigi, Steger-May Karen, Schechtman Kenneth B, Klein Samuel, Ehsani Ali A, Holloszy John O
Division of Geriatrics and Nutritional Sciences, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA.
J Appl Physiol (1985). 2007 Feb;102(2):634-40. doi: 10.1152/japplphysiol.00853.2006. Epub 2006 Nov 9.
Caloric restriction (CR) results in fat loss; however, it may also result in loss of muscle and thereby reduce strength and aerobic capacity (VO2 max). These effects may not occur with exercise-induced weight loss (EX) because of the anabolic effects of exercise on heart and skeletal muscle. We tested the hypothesis that CR reduces muscle size and strength and VO2 max, whereas EX preserves or improves these parameters. Healthy 50- to 60-yr-old men and women (body mass index of 23.5-29.9 kg/m2) were studied before and after 12 mo of weight loss by CR (n = 18) or EX (n = 16). Lean mass was assessed by dual-energy X-ray absorptiometry, thigh muscle volume by MRI, isometric and isokinetic knee flexor strength by dynamometry, and treadmill VO2 max by indirect calorimetry. Both interventions caused significant decreases in body weight (CR: -10.7 +/- 1.4%, EX: -9.5 +/- 1.5%) and lean mass (CR: -3.5 +/- 0.7%, EX: -2.2 +/- 0.8%), with no significant differences between groups. Significant decreases in thigh muscle volume (-6.9 +/- 0.8%) and composite knee flexion strength (-7.2 +/- 3%) occurred in the CR group only. Absolute VO2 max decreased significantly in the CR group (-6.8 +/- 2.3%), whereas the EX group had significant increases in both absolute (+15.5 +/- 2.4%) and relative (+28.3 +/- 3.0%) VO2 max. These data provide evidence that muscle mass and absolute physical work capacity decrease in response to 12 mo of CR but not in response to a similar weight loss induced by exercise. These findings suggest that, during EX, the body adapts to maintain or even enhance physical performance capacity.
热量限制（CR）会导致脂肪减少；然而，它也可能导致肌肉流失，从而降低力量和有氧能力（最大摄氧量，VO2 max）。由于运动对心脏和骨骼肌具有合成代谢作用，运动诱导的体重减轻（EX）可能不会产生这些影响。我们检验了以下假设：热量限制会减小肌肉尺寸、降低力量和最大摄氧量，而运动则能维持或改善这些参数。对年龄在50至60岁、体重指数为23.5至29.9 kg/m²的健康男性和女性进行了研究，在通过热量限制（n = 18）或运动（n = 16）进行12个月的体重减轻前后进行了评估。通过双能X线吸收法评估瘦体重，通过磁共振成像评估大腿肌肉体积，通过测力计评估等长和等速膝关节屈肌力量，通过间接量热法评估跑步机上的最大摄氧量。两种干预措施均导致体重显著下降（热量限制组：-10.7 +/- 1.4%，运动组：-9.5 +/- 1.5%）和瘦体重下降（热量限制组：-3.5 +/- 0.7%，运动组：-2.2 +/- 0.8%），两组之间无显著差异。仅热量限制组的大腿肌肉体积（-6.9 +/- 0.8%）和复合膝关节屈曲力量（-7.2 +/- 3%）显著下降。热量限制组的绝对最大摄氧量显著下降（-6.8 +/- 2.3%），而运动组的绝对最大摄氧量（+15.5 +/- 2.4%）和相对最大摄氧量（+28.3 +/- 3.0%）均显著增加。这些数据表明，12个月的热量限制会导致肌肉量和绝对体力工作能力下降，但运动诱导的类似体重减轻则不会。这些发现表明，在运动期间，身体会进行适应性调整以维持甚至增强身体运动能力。
