Sloot Lizeth H, Weide Guido, van der Krogt Marjolein M, Desloovere Kaat, Harlaar Jaap, Buizer Annemieke I, Bar-On Lynn
Amsterdam UMC, Vrije Universiteit Amsterdam, Department of Rehabilitation Medicine, Amsterdam Movement Sciences, Amsterdam, Netherlands.
Institute of Computer Engineering (ZITI), Heidelberg University, Heidelberg, Germany.
Front Bioeng Biotechnol. 2021 Feb 16;8:591004. doi: 10.3389/fbioe.2020.591004. eCollection 2020.
In neurological diseases, muscles often become hyper-resistant to stretch due to hyperreflexia, an exaggerated stretch reflex response that is considered to primarily depend on the muscle's stretch velocity. However, there is still limited understanding of how different biomechanical triggers applied during clinical tests evoke these reflex responses. We examined the effect of imposing a rotation with increasing velocity vs. increasing acceleration on triceps surae muscle repsonse in children with spastic paresis (SP) and compared the responses to those measured in typically developing (TD) children. A motor-operated ankle manipulator was used to apply different bell-shaped movement profiles, with three levels of maximum velocity (70, 110, and 150°/s) and three levels of maximum acceleration (500, 750, and 1,000°/s). For each profile and both groups, we evaluated the amount of evoked triceps surae muscle activation. In SP, we evaluated two additional characteristics: the intensity of the response (peak EMG burst) and the time from movement initiation to onset of the EMG burst. As expected, the amount of evoked muscle activation was larger in SP compared to TD (all muscles: < 0.001) and only sensitive to biomechanical triggers in SP. Further investigation of the responses in SP showed that peak EMG bursts increased in profiles with higher peak velocity (lateral gastrocnemius: = 0.04), which was emphasized by fair correlations with increased velocity at EMG burst onset (all muscles: > 0.33-0.36, ≤ 0.008), but showed no significant effect for acceleration. However, the EMG burst was evoked faster with higher peak acceleration (all muscles < 0.001) whereas it was delayed in profiles with higher peak velocity (medial gastrocnemius and soleus: < 0.006). We conclude that while exaggerated response intensity (peak EMG burst) seems linked to stretch velocity, higher accelerations seem to evoke faster responses (time to EMG burst onset) in triceps surae muscles in SP. Understanding and controlling for the distinct effects of different biological triggers, including velocity, acceleration but also length and force of the applied movement, will contribute to the development of more precise clinical measurement tools. This is especially important when aiming to understand the role of hyperreflexia during functional movements where the biomechanical inputs are multiple and changing.
在神经系统疾病中，由于反射亢进，肌肉通常会对拉伸产生过度抵抗，反射亢进是一种过度的牵张反射反应，主要取决于肌肉的拉伸速度。然而，对于临床测试中施加的不同生物力学触发因素如何引发这些反射反应，人们的了解仍然有限。我们研究了在痉挛性麻痹（SP）儿童中，以速度增加与加速度增加的方式进行旋转对小腿三头肌反应的影响，并将这些反应与正常发育（TD）儿童的测量结果进行比较。使用电动踝关节操纵器施加不同的钟形运动模式，具有三个最大速度水平（70、110和150°/秒）和三个最大加速度水平（500、750和1000°/秒）。对于每个模式和两组儿童，我们评估了诱发的小腿三头肌激活量。在SP组中，我们还评估了另外两个特征：反应强度（肌电图峰值爆发）和从运动开始到肌电图爆发开始的时间。正如预期的那样，与TD组相比，SP组诱发的肌肉激活量更大（所有肌肉：<0.001），并且仅对SP组中的生物力学触发因素敏感。对SP组反应的进一步研究表明，在峰值速度较高的模式中，肌电图峰值爆发增加（外侧腓肠肌：=0.04），这在肌电图爆发开始时与速度增加的适度相关性中得到强调（所有肌肉：>0.33 - 0.36，≤0.008），但对加速度没有显著影响。然而，峰值加速度较高时，肌电图爆发诱发得更快（所有肌肉<0.001），而在峰值速度较高的模式中则延迟（内侧腓肠肌和比目鱼肌：<0.006）。我们得出结论，虽然过度的反应强度（肌电图峰值爆发）似乎与拉伸速度有关，但较高的加速度似乎会在SP组的小腿三头肌中引发更快的反应（肌电图爆发开始时间）。了解并控制不同生物触发因素（包括速度、加速度，以及所施加运动的长度和力）的独特影响，将有助于开发更精确的临床测量工具。当旨在了解反射亢进在生物力学输入多样且不断变化的功能运动中的作用时，这一点尤为重要。
