School of Basic and Medical Biosciences, Faculty of Life Science and Medicine, King's College London, London, UK.
J Anat. 2023 May;242(5):745-753. doi: 10.1111/joa.13821. Epub 2023 Jan 31.
Human standing is the anatomical and functional framework for independent movement. The study of weight bearing during standing and movement is crucial to support the development of technology aimed at restoring independent gait, where unsupported weight bearing is still elusive. This study aims to determine muscle and spinal activation at different gravitational loads in young, healthy individuals to provide potential patterns of spinal stimulation for standing. Muscle activity was recorded with surface electromyography (EMG) from 18 healthy participants at different body angles while on a motorised plinth. The body angles tested and the relative gravitational loadings were: 0 deg (supine) corresponding to 0% of total body weight (BW), 15 deg (26% BW), 30 deg (50% BW), 45 deg (71% BW), 60 deg (87% BW), 75 deg (97% BW), upright on and off the plinth (100% BW). The muscles recorded were soleus, gastrocnemius medialis and lateralis, tibialis anterior, adductor longus, peroneus longus, vastus medialis and lateralis, rectus femoris, sartorius, extensor digitorum longus, semimembranosus, semitendinosus, biceps femoris, gracilis, rectus abdominis, external oblique, erector spinae and latissimus dorsi. From the recorded muscle activity, spinal activation maps were calculated. Despite high variability in EMG data, the group muscle activity changed with body angle. Vastus lateralis became activated at 60 deg (87% BW), soleus became activated at 75 deg, and the gastrocnemii at 90 deg. The spinal segments that showed significant differences in mean activation between angles were the fifth lumbar L5 and the first sacral S1 segments. The data from this study suggest that weight-bearing independent standing could be achieved with increased activation of a limited number of superficial muscles tested, and 87% BW is a critical loading for increased muscle activation compared to the supine position. The spinal activation in the lower lumbar and sacral segments shows the involvement of these regions in maintaining weight-bearing standing. By reproducing this pattern of muscle and spinal segment activity through tonic stimulation, we speculate that restoration of independent standing and walking may be possible for patients following spinal cord injuries.
人站立是独立运动的解剖学和功能框架。研究站立和运动时的承重对于支持旨在恢复独立步态的技术的发展至关重要，而独立承重仍然难以实现。本研究旨在确定年轻健康个体在不同重力负荷下的肌肉和脊柱激活情况，为站立提供潜在的脊柱刺激模式。通过在电动平台上以不同的身体角度记录来自 18 名健康参与者的表面肌电图（EMG）来记录肌肉活动。测试的身体角度和相对重力负荷分别为：0°（仰卧）对应于约 0%的全身重量（BW），15°（26% BW），30°（50% BW），45°（71% BW），60°（87% BW），75°（97% BW），在平台上和平台下的直立（100% BW）。记录的肌肉是比目鱼肌、腓肠肌内侧和外侧、胫骨前肌、长收肌、腓骨长肌、股外侧肌和股直肌、股直肌、缝匠肌、伸趾长肌、半膜肌、半腱肌、股二头肌、股薄肌、腹直肌、腹外斜肌、竖脊肌和背阔肌。从记录的肌肉活动中计算出脊柱激活图。尽管 EMG 数据存在高度变异性，但组内肌肉活动随身体角度而变化。股外侧肌在 60°（~87% BW）时被激活，比目鱼肌在 75°时被激活，而腓肠肌在 90°时被激活。在角度之间的平均激活方面显示出显著差异的脊柱节段是第五腰椎 L5 和第一骶骨 S1 节段。本研究的数据表明，通过增加测试的少数浅层肌肉的激活，可能实现独立承重站立，与仰卧位相比，87% BW 是增加肌肉激活的关键负荷。较低腰椎和骶骨节段的脊柱激活表明这些区域参与维持承重站立。通过通过紧张性刺激再现这种肌肉和脊柱节段活动的模式，我们推测通过脊髓损伤后患者可能恢复独立站立和行走。
