Department of Physiotherapy, Centre for Health Exercise and Sports Medicine, University of Melbourne, Australia.
Department of Exercise and Sport Science, University of North Carolina at Chapel Hill.
J Athl Train. 2018 Feb;53(2):135-143. doi: 10.4085/1062-6050-306-16. Epub 2018 Jan 19.
Aberrant biomechanics may affect force attenuation at the knee during dynamic activities, potentially increasing the risk of sustaining a knee injury or hastening the development of osteoarthritis after anterior cruciate ligament reconstruction (ACLR). Impaired quadriceps neuromuscular function has been hypothesized to influence the development of aberrant biomechanics.
To determine the association between quadriceps neuromuscular function (strength, voluntary activation, and spinal-reflex and corticomotor excitability) and sagittal-plane knee biomechanics during jump landings in individuals with ACLR.
Cross-sectional study.
Research laboratory.
Twenty-eight individuals with unilateral ACLR (7 men, 21 women; age = 22.4 ± 3.7 years, height = 1.69 ± 0.10 m, mass = 69.4 ± 10.1 kg, time postsurgery = 52 ± 42 months).
MAIN OUTCOME MEASURE(S): We quantified quadriceps spinal-reflex excitability via the Hoffmann reflex normalized to maximal muscle response (H : M ratio), corticomotor excitability via active motor threshold, strength as knee-extension maximal voluntary isometric contraction (MVIC), and voluntary activation using the central activation ratio (CAR). In a separate session, sagittal-plane kinetics (peak vertical ground reaction force [vGRF] and peak internal knee-extension moment) and kinematics (knee-flexion angle at initial contact, peak knee-flexion angle, and knee-flexion excursion) were collected during the loading phase of a jump-landing task. Separate bivariate associations were performed between the neuromuscular and biomechanical variables.
In the ACLR limb, greater MVIC was associated with greater peak knee-flexion angle ( r = 0.38, P = .045) and less peak vGRF ( r = -0.41, P = .03). Greater CAR was associated with greater peak internal knee-extension moment (ρ = -0.38, P = .045), and greater H : M ratios were associated with greater peak vGRF ( r = 0.45, P = .02).
Greater quadriceps MVIC and CAR may provide better energy attenuation during a jump-landing task. Individuals with greater peak vGRF in the ACLR limb possibly require greater spinal-reflex excitability to attenuate greater loading during dynamic movements.
在动态活动中，异常的生物力学可能会影响膝关节的力衰减，从而增加膝关节受伤的风险或加速前交叉韧带重建（ACLR）后的骨关节炎发展。人们假设股四头肌神经肌肉功能受损会影响异常生物力学的发展。
确定 ACLR 后个体在跳跃着陆时股四头肌神经肌肉功能（力量、自愿激活以及脊髓反射和皮质运动兴奋性）与矢状面膝关节生物力学之间的关系。
横断面研究。
研究实验室。
28 名单侧 ACLR 患者（7 名男性，21 名女性；年龄=22.4±3.7 岁，身高=1.69±0.10 m，体重=69.4±10.1 kg，手术后时间=52±42 个月）。
我们通过 Hoffmann 反射与最大肌肉反应的比值（H：M 比）量化股四头肌脊髓反射兴奋性，通过主动运动阈值量化皮质运动兴奋性，通过膝关节伸展最大自主等长收缩（MVIC）量化力量，通过中央激活比（CAR）量化自愿激活。在单独的会议中，在跳跃着陆任务的加载阶段收集矢状面动力学（垂直地面反作用力峰值[vGRF]和峰值膝关节内伸力矩）和运动学（初始接触时的膝关节屈曲角度、峰值膝关节屈曲角度和膝关节屈曲幅度）。对神经肌肉和生物力学变量之间的单独双变量相关性进行了分析。
在 ACLR 肢体中，MVIC 越大，峰值膝关节屈曲角度越大（r=0.38，P=0.045），vGRF 峰值越小（r=-0.41，P=0.03）。CAR 越大，峰值膝关节内伸力矩越大（ρ=-0.38，P=0.045），H：M 比值越大，vGRF 峰值越大（r=0.45，P=0.02）。
更大的股四头肌 MVIC 和 CAR 可能在跳跃着陆任务中提供更好的能量衰减。在 ACLR 肢体中 vGRF 峰值较大的个体可能需要更大的脊髓反射兴奋性来减轻动态运动中的更大负荷。
