Department of Sports Medicine, Medical Clinic, University Hospital Heidelberg, Heidelberg, Germany.
Olympic Training Center, Heidelberg, Germany.
PLoS One. 2021 Oct 14;16(10):e0258635. doi: 10.1371/journal.pone.0258635. eCollection 2021.
Impaired muscle regeneration has repeatedly been described after anterior cruciate ligament reconstruction (ACL-R). The results of recent studies provided some evidence for negative alterations in knee extensor muscles after ACL-R causing persisting strength deficits in spite of the regain of muscle mass. Accordingly, we observed that 12 weeks of concentric/eccentric quadriceps strength training with eccentric overload (CON/ECC+) induced a significantly greater hypertrophy of the atrophied quadriceps muscle after ACL-R than conventional concentric/eccentric quadriceps strength training (CON/ECC). However, strength deficits persisted and there was an unexpected increase in the proportion of slow type I fibers instead of the expected shift towards a faster muscle phenotype after CON/ECC+. In order to shed further light on muscle recovery after ACL-R, the steady-state levels of 84 marker mRNAs were analyzed in biopsies obtained from the vastus lateralis muscle of 31 subjects before and after 12 weeks of CON/ECC+ (n = 18) or CON/ECC strength training (n = 13) during rehabilitation after ACL-R using a custom RT2 Profiler PCR array. Significant (p < 0.05) changes were detected in the expression of 26 mRNAs, several of them involved in muscle wasting/atrophy. A different pattern with regard to the strength training mode was observed for 16 mRNAs, indicating an enhanced hypertrophic stimulus, mechanical sensing or fast contractility after CON/ECC+. The effects of the type of autograft (quadriceps, QUAD, n = 19, or semitendinosus tendon, SEMI, n = 12) were reflected in the lower expression of 6 mRNAs involved in skeletal muscle hypertrophy or contractility in QUAD. In conclusion, the greater hypertrophic stimulus and mechanical stress induced by CON/ECC+ and a beginning shift towards a faster muscle phenotype after CON/ECC+ might be indicated by significant gene expression changes as well as still ongoing muscle wasting processes and a negative impact of QUAD autograft.
前交叉韧带重建 (ACL-R) 后，肌肉再生受损的情况已反复被描述。最近的研究结果提供了一些证据，表明 ACL-R 后膝关节伸肌发生了负性变化，尽管肌肉量得到恢复，但仍持续存在力量缺陷。因此，我们观察到，与传统的等长/离心股四头肌力量训练 (CON/ECC) 相比，12 周的等长/离心股四头肌力量训练（CON/ECC+）外加离心超负荷训练导致 ACL-R 后萎缩的股四头肌发生了更大的肥大。然而，力量缺陷仍然存在，并且在 CON/ECC+后，出乎意料地增加了慢型 I 型纤维的比例，而不是预期的向更快的肌肉表型转变。为了进一步阐明 ACL-R 后的肌肉恢复情况，我们使用定制的 RT2 Profiler PCR 阵列分析了 31 名受试者在 ACL-R 康复期间接受 12 周 CON/ECC+（n = 18）或 CON/ECC 力量训练（n = 13）前后取自股外侧肌的活检标本中的 84 种标记 mRNA 的稳态水平。在 26 种 mRNA 的表达中检测到显著（p < 0.05）的变化，其中一些与肌肉萎缩/萎缩有关。对于 16 种 mRNA，观察到与力量训练模式有关的不同模式，表明 CON/ECC+后会增强肥大刺激、机械感知或快速收缩性。同种异体移植物（股四头肌，QUAD，n = 19，或半腱肌腱，SEMI，n = 12）的类型反映在涉及骨骼肌肥大或收缩性的 6 种 mRNA 的较低表达中。总之，CON/ECC+引起的更大的肥大刺激和机械应力以及 CON/ECC+后开始向更快的肌肉表型转变，可能由显著的基因表达变化以及持续存在的肌肉萎缩过程和 QUAD 同种异体移植物的负面影响来指示。
