Kalaoglu Eser, Yildiz Nilgun, Sezikli Selim, Ozkan Ismet Alkim, Karacan Ilhan, Türker Kemal Sitki
İstanbul Physical Therapy Rehabilitation Training and Research Hospital, Istanbul, Türkiye.
Department of Physiotherapy and Rehabilitation, Faculty of Health Sciences, Istanbul Gelişim University, Istanbul, Türkiye.
Eur J Appl Physiol. 2025 Aug 29. doi: 10.1007/s00421-025-05960-6.
The short-latency reflex (SLR), which occurs immediately after ground contact during jumping, is traditionally attributed to a muscle spindle-mediated stretch reflex, with a longer latency explained by slow muscle stretching. However, emerging evidence suggests that the bone myoregulation reflex (BMR) may provide a more physiologically parsimonious and biomechanically integrated explanation for this response.
This study compared the latencies of these reflexes and assessed the mechanical stimulus transmission delay to the muscle during impact.
Two experiments were performed in healthy adults. Experiment 1 measured the soleus tendon reflex (T-reflex), SLR, and BMR latencies via surface electromyography (EMG). Experiment 2 recorded delays from the mechanical stimulus to the muscle belly using intramuscular EMG.
The median latencies in Experiment 1 were 35.0 ms (T-reflex), 45.8 ms (SLR), and 43.0 ms (BMR). The SLR and BMR latencies were significantly longer than the T-reflex latencies (p = 3.6 × 10⁻). There was no difference between the SLR and BMR. Experiment 2 showed mechanical transmission delays of 4.31 ms (tendon stretch), 3.31 ms (tap), and 2.83 ms (whole-body vibration), without significant differences. The ~ 11 ms longer SLR latency than the T-reflex cannot be explained by slow muscle stretching. Normalized soleus EMG signals during landing (feedforward) were positively correlated with the SLR amplitude (feedback) (r = 0.554, p = 0.0003).
The latency characteristics of the SLR suggest that it more closely resembles the BMR than the classical stretch reflex does. It is speculated that as a bone-protective mechanism, BMR may underlie reflexive muscle contractions that deliver load-induced protective feedback during impact, potentially preserving both bone and muscle-tendon integrity.
短潜伏期反射（SLR）在跳跃过程中与地面接触后立即出现，传统上归因于肌梭介导的牵张反射，潜伏期较长则解释为肌肉缓慢拉伸。然而，新出现的证据表明，骨肌调节反射（BMR）可能为这种反应提供更符合生理简约性和生物力学整合性的解释。
本研究比较了这些反射的潜伏期，并评估了冲击过程中机械刺激向肌肉的传输延迟。
在健康成年人中进行了两项实验。实验1通过表面肌电图（EMG）测量比目鱼肌腱反射（T反射）、SLR和BMR潜伏期。实验2使用肌内EMG记录从机械刺激到肌腹的延迟。
实验1中的中位潜伏期分别为35.0毫秒（T反射）、45.8毫秒（SLR）和43.0毫秒（BMR）。SLR和BMR潜伏期显著长于T反射潜伏期（p = 3.6×10⁻）。SLR和BMR之间没有差异。实验2显示机械传输延迟分别为4.31毫秒（肌腱拉伸）、3.31毫秒（轻敲）和2.83毫秒（全身振动），无显著差异。SLR潜伏期比T反射长约11毫秒无法用肌肉缓慢拉伸来解释。着陆（前馈）期间比目鱼肌EMG信号的标准化与SLR幅度（反馈）呈正相关（r = 0.554，p = 0.0003）。
SLR的潜伏期特征表明，它与BMR的相似性比经典牵张反射更高。据推测，作为一种骨保护机制，BMR可能是反射性肌肉收缩的基础，在冲击过程中提供负荷诱导的保护性反馈，可能保护骨骼和肌肉肌腱的完整性。
