Campus Health Services, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
J Athl Train. 2012 Jul-Aug;47(4):406-13. doi: 10.4085/1062-6050-47.4.17.
Decreased sagittal-plane motion at the knee during dynamic tasks has been reported to increase impact forces during landing, potentially leading to knee injuries such as anterior cruciate ligament rupture.
To describe the relationship between lower extremity muscle activity and knee-flexion angle during a jump-landing task.
Cross-sectional study.
Research laboratory.
Thirty recreationally active volunteers (15 men, 15 women: age = 21.63 ± 2.01 years, height = 173.95 ± 11.88 cm, mass = 72.57 ± 14.25 kg).
INTERVENTION(S): Knee-flexion angle and lower extremity muscle activity were collected during 10 trials of a jump-landing task.
MAIN OUTCOME MEASURE(S): Simple correlation analyses were performed to determine the relationship between each knee-flexion variable (initial contact, peak, and displacement) and electromyographic amplitude of the gluteus maximus (GMAX), quadriceps (VMO and VL), hamstrings, gastrocnemius, and quadriceps : hamstring (Q : H) ratio. Separate forward stepwise multiple regressions were conducted to determine which combination of muscle activity variables predicted each knee-flexion variable.
During preactivation, VMO and GMAX activity and the Q : H ratio were negatively correlated with knee-flexion angle at initial contact (VMO: r = 0.382, P = .045; GMAX: r = 0.385, P = .043; Q : H ratio: r = 0.442, P = .018). The VMO, VL, and GMAX deceleration values were negatively correlated with peak knee-flexion angle (VMO: r = 0.687, P = .001; VL: r = 0.467, P = .011; GMAX: r = 0.386, P = .043). The VMO and VL deceleration values were negatively correlated with knee-flexion displacement (VMO: r = 0.631, P = .001; VL: r = 0.453, P = .014). The Q : H ratio and GM activity predicted 34.7% of the variance in knee-flexion angle at initial contact (P = .006). The VMO activity predicted 47.1% of the variance in peak knee-flexion angle (P = .001). The VMO and VL activity predicted 49.5% of the variance in knee-flexion displacement (P = .001).
Greater quadriceps and GMAX activation and less hamstrings and gastrocnemius activation were correlated with smaller knee-flexion angles. This landing strategy may predispose an individual to increased impact forces due to the negative influence on knee-flexion position.
在动态任务中，膝关节矢状面运动减少已被报道会增加落地时的冲击力，从而导致前交叉韧带断裂等膝关节损伤。
描述跳跃落地任务中下肢肌肉活动与膝关节屈曲角度之间的关系。
横断面研究。
研究实验室。
30 名休闲活跃志愿者（15 名男性，15 名女性：年龄=21.63±2.01 岁，身高=173.95±11.88cm，体重=72.57±14.25kg）。
在 10 次跳跃落地任务中收集膝关节屈曲角度和下肢肌肉活动数据。
简单相关分析用于确定每个膝关节屈曲变量（初始接触、峰值和位移）与臀大肌（GMAX）、股四头肌（VMO 和 VL）、腘绳肌、腓肠肌和股四头肌：比（Q：H）的关系。分别进行向前逐步多元回归，以确定哪种肌肉活动变量组合可以预测每个膝关节屈曲变量。
在预激活期间，VMO 和 GMAX 活动以及 Q：H 比与初始接触时的膝关节屈曲角度呈负相关（VMO：r=0.382，P=0.045；GMAX：r=0.385，P=0.043；Q：H 比：r=0.442，P=0.018）。VMO、VL 和 GMAX 的减速值与峰值膝关节屈曲角度呈负相关（VMO：r=0.687，P=0.001；VL：r=0.467，P=0.011；GMAX：r=0.386，P=0.043）。VMO 和 VL 的减速值与膝关节屈曲位移呈负相关（VMO：r=0.631，P=0.001；VL：r=0.453，P=0.014）。Q：H 比和 GM 活动可预测初始接触时膝关节屈曲角度变化的 34.7%（P=0.006）。VMO 活动可预测峰值膝关节屈曲角度变化的 47.1%（P=0.001）。VMO 和 VL 活动可预测膝关节屈曲位移变化的 49.5%（P=0.001）。
股四头肌和 GMAX 激活增加，腘绳肌和腓肠肌激活减少与膝关节屈曲角度减小相关。这种着陆策略可能会由于对膝关节位置的负面影响而导致冲击力增加，从而使个体易受影响。
