Changes in muscle strength, muscle fibre size and myofibrillar gene expression after immobilization and retraining in humans
Changes in muscle strength, muscle fibre size and myofibrillar gene expression after immobilization and retraining in humans
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DOI：
10.1111/j.1469-7793.2000.00293.x
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发表时间：
2000-04-01
影响因子：
5.5
通讯作者：
Dohm, L
中科院分区：
文献类型：
--
作者：
Hortobágyi, T;Dempsey, L;Dohm, L
1. 对 48 名男性和女性进行 3 周的膝关节固定以及 12 周的 1866 次偏心、向心或混合收缩再训练后，检查肌肉力量、股外侧肌纤维特征和肌球蛋白重链 (MyoHC) 基因表达的变化。2.固定使偏心、同心和等长强度降低了 47%。经过 2 周的自然恢复后，平均力量仍然下降 11%。偏心混合训练与向心再训练相比，力量恢复速度更快，偏心和等长力量增益更大。 3．固定使 I 型、IIa 型和 IIx 型肌纤维面积分别减少 13%、10% 和 10%，从固定中自然恢复 2 周后，这些纤维比基线小 5%。离心训练后，I、IIa 和 IIx 型纤维相对于基线的肥大分别为 10%、16% 和 16%，混合训练后分别为 11%、9% 和 10%（均 P < 0.05），超过了向心训练后的 4%、5% 和 5%。偏心训练后IIa型和IIx型纤维增大最大。4．总 RNA/湿肌肉重量以及 I 型、IIa 型和 IIx MyoHC mRNA 水平在固定和再训练后没有不同变化。固定将 I 型 MyoHC mRNA 的表达下调至基线的 0.72 倍，运动训练将其上调至基线的 0.95 倍。 IIa 型 MyoHC mRNA 没有发生变化。固定和运动训练分别上调 IIx 型 MyoHC mRNA 2.9 倍和 1.2 倍。对于固定段，I、IIa 和 IIx 型纤维面积与 I、IIa 和 IIx 型 MyoHC mRNA 相关（分别为 r = 0.66、r = 0.07 和 r = -0.71）。 5．目前的数据强调了肌肉延长在人类神经肌肉功能和适应中的作用。
1. Changes in muscle strength, vastus lateralis fibre characteristics and myosin heavy-chain (MyoHC) gene expression were examined in 48 men and women following 3 weeks of knee immobilization and after 12 weeks of retraining with 1866 eccentric, concentric or mixed contractions.2. Immobilization reduced eccentric, concentric and isometric strength by 47%. After 2 weeks of spontaneous recovery there still was an average strength deficit of 11%. With eccentric and mixed compared with concentric retraining the rate of strength recovery was faster and the eccentric and isometric strength gains greater.3. Immobilization reduced type I, IIa and IIx muscle fibre areas by 13, 10 and 10%, respectively and after 2 weeks of spontaneous recovery from immobilization these fibres were 5% smaller than at baseline. Hypertrophy of type I, IIa and IIx fibres relative to baseline was 10, 16 and 16% after eccentric and 11, 9 and 10% after mixed training (all P < 0.05), exceeding the 4, 5 and 5% gains after concentric training. Type IIa and IIx fibre enlargements were greatest after eccentric training.4. Total RNA/wet muscle weight and type I, IIa and IIx MyoHC mRNA levels did not change differently after immobilization and retraining. Immobilization downregulated the expression of type I MyoHC mRNA to 0.72-fold of baseline and exercise training upregulated it to 0.95 of baseline. No changes occurred in type IIa MyoHC mRNA. Immobilization and exercise training upregulated type IIx MyoHC mRNA 2.9-fold and 1.2-fold, respectively. For the immobilization segment, type I, IIa and IIx fibre area and type I, IIa and IIx MyoHC mRNA correlated (r = 0.66, r = 0.07 and r = -0.71, respectively).5. The present data underscore the role muscle lengthening plays in human neuromuscular function and adaptation.