Department of Exercise Sciences, Human Performance Research Center, Brigham Young University, 120-E Richards Bldg., Provo, UT 84602, USA.
Eur J Appl Physiol. 2010 Mar;108(4):771-8. doi: 10.1007/s00421-009-1279-z.
This study examined the impact of resistance exercise volume on myoD and myogenin in rodent quadriceps muscle. Six-month-old male Sprague-Dawley rats (316 +/- 2 g) performed either low-volume (LV; 10 sets x 10 contractions) or high-volume (HV; 20 sets x 10 contractions) resistance exercise at 75% one-repetition maximum. Muscles were analyzed for myogenin and myoD mRNA and protein expression 6, 12, 24 and 48 h post-exercise. In red quadriceps (RQ), myogenin mRNA was significantly elevated at 6 h following LV and this response was greater than HV at 6 h, while myogenin protein was significantly increased at 6 and 12 h following LV but only at 12 h following HV (P < 0.05). MyoD mRNA was increased at 6 and 12 h following LV and at 12 h following HV, while myoD protein was slightly decreased (LV; P < 0.05) or unchanged over time (HV). No changes were detected within the white quadriceps muscle. We conclude that acute resistance exercise can activate myogenin and myoD expression levels in RQ, but when exercise volume is doubled these myogenic responses are not proportional but delayed and blunted possibly because of excessive damage/injury. Further work is needed to determine the consequences of these specific myogenic responses on muscle hypertrophy following high-volume resistance exercise training.
本研究探讨了抗阻运动训练量对啮齿类动物股四头肌 myoD 和 myogenin 的影响。6 月龄雄性 Sprague-Dawley 大鼠（316 ± 2 g）分别进行低训练量（10 组×10 次收缩）或高训练量（20 组×10 次收缩）抗阻运动训练，负荷为 1 次最大重复值的 75%。运动后 6、12、24 和 48 h 分析肌肉 myogenin 和 myoD mRNA 和蛋白表达。在红肌（RQ）中，LV 后 6 h myogenin mRNA 显著升高，且该反应高于 HV 组；而 LV 组 myogenin 蛋白在 6 和 12 h 显著升高，HV 组仅在 12 h 升高（P < 0.05）。LV 组 myoD mRNA 在 6 和 12 h 升高，HV 组在 12 h 升高，而 myoD 蛋白在 LV 组稍有下降（P < 0.05）或随时间不变（HV 组）。在白肌中未检测到变化。综上，急性抗阻运动可激活 RQ 中的 myogenin 和 myoD 表达水平，但当运动训练量加倍时，这些肌源性反应不成比例，而是延迟和减弱，可能是因为过度的损伤。需要进一步研究以确定这些特定的肌源性反应对高训练量抗阻运动训练后肌肉肥大的影响。
