Amirova Liubov E, Plehuna Anastasija, Rukavishnikov Ilya V, Saveko Alina A, Peipsi Aleko, Tomilovskaya Elena S
Laboratory of Gravitational Physiology of the Sensorimotor System, Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia.
King's College London, Centre of Human & Applied Physiological Sciences, London, United Kingdom.
Front Physiol. 2021 May 6;12:661922. doi: 10.3389/fphys.2021.661922. eCollection 2021.
A decrease in muscle tone induced by space flight requires a standardized assessment of changes to control the state of the neuromuscular system. This study is a step toward the development of a unified protocol, aimed at determining the initial effect of the presence or withdrawal of support on muscle tone, the effects of a 2-h supportlessness in Dry Immersion (DI) experiments, and the changes in muscle tone depending on the site of measurement. To perform measurements of changes in muscle tone, we used a MyotonPRO device. The list of muscles that we assessed includes: trunk - mm. deltoideus posterior, trapezius, erector spinae; leg - mm. biceps femoris, rectus femoris, tibialis anterior, soleus, gastrocnemius; foot - m. flexor digitorum brevis, tendo Achillis, aponeurosis plantaris. The study involved 12 healthy volunteers (6 men, 6 women) without musculoskeletal disorders and aged 32.8 ± 1.6 years. At the start of DI, there was a significant decrease in muscle tone of the following muscles: mm. tibialis anterior (-10.9%), soleus (-9.6%), erector spinae (-14.4%), and the tendo Achillis (-15.3%). The decrease continued to intensify over the next 2 h. In contrast, the gastrocnemius muscle demonstrated an increase in muscle tone (+7.5%) 2 h after the start of DI compared to the immediate in-bath baseline. Muscle tone values were found to be site-dependent and varied in different projections of mm. erector spinae and soleus. In previous experiments, we observed a high sensitivity of the myotonometry technique, which was confirmed in this study. To make it possible to compare data from different studies, a standardized protocol for measuring muscle tone for general use in gravitational physiology needs to be developed.
太空飞行引起的肌张力下降需要对变化进行标准化评估，以控制神经肌肉系统的状态。本研究朝着制定统一方案迈出了一步，旨在确定支撑的存在或撤除对肌张力的初始影响、干浸（DI）实验中2小时无支撑状态的影响以及肌张力随测量部位的变化。为了测量肌张力的变化，我们使用了MyotonPRO设备。我们评估的肌肉包括：躯干——三角肌后束、斜方肌、竖脊肌；腿部——股二头肌、股直肌、胫骨前肌、比目鱼肌、腓肠肌；足部——趾短屈肌、跟腱、足底腱膜。该研究纳入了12名无肌肉骨骼疾病的健康志愿者（6名男性，6名女性），年龄为32.8±1.6岁。在DI开始时，以下肌肉的肌张力显著下降：胫骨前肌（-10.9%）、比目鱼肌（-9.6%）、竖脊肌（-14.4%）和跟腱（-15.3%）。在接下来的2小时内，这种下降继续加剧。相比之下，与入浴后即刻基线相比，腓肠肌在DI开始2小时后肌张力增加（+7.5%）。发现肌张力值与测量部位有关，在竖脊肌和比目鱼肌的不同投影中有所不同。在之前的实验中，我们观察到肌张力测量技术具有高敏感性，本研究证实了这一点。为了能够比较不同研究的数据，需要制定一种在重力生理学中普遍使用的测量肌张力的标准化方案。
