Department of Kinesiology, Southern Illinois University Carbondale, Carbondale, IL, United States of America.
Department of Athletic Training and Exercise Physiology, Midwestern State University, Wichita Falls, TX, United States of America.
PLoS One. 2020 Feb 21;15(2):e0219648. doi: 10.1371/journal.pone.0219648. eCollection 2020.
External loading of the ligamentous tissues induces mechanical creep, which modifies neuromuscular response to perturbations. It is not well understood how ligamentous creep affects athletic performance and contributes to modifications of knee biomechanics during functional tasks.
HYPOTHESIS/PURPOSE: The purpose of this study was to examine the mechanical and neuromuscular responses to single leg drop landing perturbations before and after passive loading of the knee joint.
Descriptive laboratory study. Male (n = 7) and female (n = 14) participants' (21.3 ± 2.1 yrs., 1.69 ± 0.09 m, 69.3 ± 13.0 kg) right hip, knee, and ankle kinematics were assessed during drop landings performed from a 30 cm height onto a force platform before and after a 10 min creep protocol. Electromyography (EMG) signals were recorded from rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), semimembranosus (SM), and biceps femoris (BF) muscles. The creep protocol involved fixing the knee joint at 35° during static loading with perpendicular loads of either 200 N (males) or 150 N (females). Maximum, minimum, range of motion (ROM), and angular velocities were assessed for the hip, knee, and ankle joints, while normalized EMG (NEMG), vertical ground reaction forces (VGRF), and rate of force development (RFD) were assessed at landing using ANOVAs. Alpha was set at 0.05.
Maximum hip flexion velocity decreased (p < 0.01). Minimum knee flexion velocity increased (p < 0.02). Minimum knee ad/abduction velocity decreased (p < 0.001). Ankle ROM decreased (p < 0.001). aVGRF decreased (p < 0.02). RFD had a non-significant trend (p = 0.076). NAEMG was significant between muscle groups (p < 0.02).
Distinct changes in velocity parameters are attributed to the altered mechanical behavior of the knee joint tissues and may contribute to changes in the loading of the leg during landing.
韧带组织的外部加载会引起机械蠕变，从而改变对扰动的神经肌肉反应。韧带蠕变如何影响运动表现以及如何在功能任务中改变膝关节生物力学尚不清楚。
假设/目的：本研究的目的是检查单腿跳下落地扰动前后膝关节被动加载后的力学和神经肌肉反应。
描述性实验室研究。男性（n=7）和女性（n=14）参与者（21.3±2.1 岁，1.69±0.09 m，69.3±13.0 kg）的右髋关节、膝关节和踝关节运动学在从 30cm 高度跳下到测力板上时进行评估，在 10 分钟蠕变方案之前和之后。从股直肌（RF）、股外侧肌（VL）、股内侧肌（VM）、半膜肌（SM）和股二头肌（BF）肌肉记录肌电图（EMG）信号。蠕变方案包括在静态加载下将膝关节固定在 35°，施加垂直载荷分别为 200N（男性）或 150N（女性）。使用 ANOVA 评估髋关节、膝关节和踝关节的最大、最小、运动范围（ROM）和角速度，同时在着陆时评估归一化 EMG（NEMG）、垂直地面反作用力（VGRF）和力发展速率（RFD）。α设置为 0.05。
最大髋关节屈曲速度降低（p<0.01）。最小膝关节屈曲速度增加（p<0.02）。最小膝关节内/外展速度降低（p<0.001）。踝关节 ROM 减小（p<0.001）。aVGRF 减小（p<0.02）。RFD 有一个非显著趋势（p=0.076）。NAEMG 在肌肉群之间有显著差异（p<0.02）。
速度参数的明显变化归因于膝关节组织机械行为的改变，可能导致着陆时腿部受力的变化。
