Willoughby Darryn S
Exercise and Molecular Kinesiology Laboratory, Department of Kinesiology, Texas Christian University, Fort Worth, TX 76129, USA.
Med Sci Sports Exerc. 2004 Apr;36(4):574-82. doi: 10.1249/01.mss.0000121952.71533.ea.
Myostatin is a negative regulator of muscle mass and its effects seem to be exacerbated by glucocorticoids; however, its response to resistance training is not well known. This study examined 12 wk of resistance training on the mRNA and protein expression of myostatin, follistatin-like related gene (FLRG), activin IIb receptor, cortisol, glucocorticoid receptor, myofibrillar protein, as well as the effects on muscle strength and mass and body composition.
Twenty-two untrained males were randomly assigned to either a resistance-training [RTR (N = 12)] or control group [CON (N = 10)]. Muscle biopsies and blood samples were obtained before and after 6 and 12 wk of resistance training. RTR trained 3 x wk(-1) using three sets of six to eight repetitions at 85-90% 1-RM on lower-body exercises, whereas CON performed no resistance training. Data were analyzed with two- and three-way ANOVA.
After 12 wk of training, RTR increased total body mass, fat-free mass, strength, and thigh volume and mass; however, they increased myostatin mRNA, myostatin, FLRG, cortisol, glucocorticoid receptor, and myofibrillar protein after 6 and 12 wk of training (P < 0.05).
Resistance training and/or increased glucocorticoid receptor expression appears to up-regulate myostatin mRNA expression. Furthermore, it is possible that any plausible decreases in skeletal muscle function from the observed increase in serum myostatin were attenuated by increased serum FLRG levels and the concomitant down-regulation of the activin IIb receptor. It is therefore concluded that the increased myostatin in response to cortisol and/or resistance training appears to have no effects on training-induced increases in muscle strength and mass.
肌肉生长抑制素是肌肉质量的负调节因子，糖皮质激素似乎会加剧其作用；然而，其对阻力训练的反应尚不明确。本研究考察了12周阻力训练对肌肉生长抑制素、卵泡抑素样相关基因（FLRG）、激活素IIb受体、皮质醇、糖皮质激素受体、肌原纤维蛋白的mRNA和蛋白表达的影响，以及对肌肉力量、质量和身体成分的影响。
22名未经训练的男性被随机分为阻力训练组[RTR（N = 12）]或对照组[CON（N = 10）]。在阻力训练6周和12周前后采集肌肉活检样本和血样。RTR组每周训练3次，进行三组下半身练习，每组6至8次重复，强度为85 - 90%的1次最大重复量（1-RM），而CON组不进行阻力训练。数据采用双向和三向方差分析。
训练12周后，RTR组增加了总体质量、去脂体重、力量、大腿体积和质量；然而，在训练6周和12周后，他们的肌肉生长抑制素mRNA、肌肉生长抑制素、FLRG、皮质醇、糖皮质激素受体和肌原纤维蛋白均增加（P < 0.05）。
阻力训练和/或糖皮质激素受体表达增加似乎上调了肌肉生长抑制素mRNA表达。此外，血清肌肉生长抑制素增加所导致的骨骼肌功能任何可能的下降，可能因血清FLRG水平升高和激活素IIb受体的伴随下调而减弱。因此得出结论，对皮质醇和/或阻力训练产生反应而增加的肌肉生长抑制素，似乎对训练诱导的肌肉力量和质量增加没有影响。
