Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands.
Med Sci Sports Exerc. 2013 Feb;45(2):230-7. doi: 10.1249/MSS.0b013e318272cf47.
Satellite cells (SCs) are of key importance in skeletal muscle tissue growth, repair, and regeneration. A single bout of high-force eccentric exercise has been demonstrated to increase mixed muscle SC content after 1-7 d of postexercise recovery. However, little is known about fiber type-specific changes in SC content and their activation status within 24 h of postexercise recovery.
Nine recreationally active young men (23 ± 1 yr) performed 300 eccentric actions of the knee extensors on an isokinetic dynamometer. Skeletal muscle biopsies from the vastus lateralis were collected preexercise and 24 h postexercise. Muscle fiber type-specific SC content and the number of activated SCs were determined by immunohistochemical analyses.
There was no difference between Type I and Type II muscle fiber SC content before exercise. SC content significantly increased 24 h postexercise in Type II muscle fibers (from 0.085 ± 0.012 to 0.133 ± 0.016 SCs per fiber, respectively; P < 0.05), whereas there was no change in Type I fibers. In accordance, activation status increased from preexercise to 24 h postexercise as demonstrated by the increase in the number of DLK1+ SCs in Type II muscle fibers (from 0.027 ± 0.008 to 0.070 ± 0.017 SCs per muscle fiber P < 0.05). Although no significant changes were observed in the number of Ki-67+ SCs, we did observe an increase in the number of proliferating cell nuclear antigen-positive SCs after 24 h of postexercise recovery.
A single bout of high-force eccentric exercise increases muscle fiber SC content and activation status in Type II but not Type I muscle fibers.
卫星细胞（SCs）在骨骼肌组织生长、修复和再生中具有重要作用。单次高强度的离心运动已被证明可在运动后 1-7 天增加混合肌 SC 含量。然而，运动后 24 小时内 SC 含量及其激活状态的纤维类型特异性变化知之甚少。
9 名有经验的年轻男性（23±1 岁）在等速测力计上进行 300 次膝关节伸肌离心运动。在运动前和运动后 24 小时采集股外侧肌的骨骼肌活检。通过免疫组织化学分析确定肌肉纤维类型特异性 SC 含量和激活的 SC 数量。
运动前，I 型和 II 型肌纤维 SC 含量之间没有差异。运动后 24 小时，II 型肌纤维的 SC 含量显著增加（从 0.085±0.012 增加到 0.133±0.016 个 SC/纤维，P<0.05），而 I 型纤维没有变化。相应地，激活状态从运动前增加到运动后 24 小时，II 型肌纤维中 DLK1+ SC 数量增加（从 0.027±0.008 增加到 0.070±0.017 个 SC/纤维，P<0.05）。尽管 Ki-67+ SC 数量没有显著变化，但我们确实观察到运动后 24 小时内增殖细胞核抗原阳性 SC 数量增加。
单次高强度离心运动可增加 II 型但不是 I 型肌纤维的肌纤维 SC 含量和激活状态。
