■尽管与着陆任务相比,双腿蹲下的动态性较低,并且对股四头肌的需求较少,双腿下蹲生物力学与前交叉韧带重建(ACLR)后持续股四头肌无力之间的关系尚不清楚.
■为了阐明ACLR后1年以上的双腿下蹲期间股四头肌力量不对称与下肢生物力学之间的关系。
■对照实验室研究。
■共纳入26名参与者(ACLR后5.5±3.8年)。使用等速股四头肌力量的肢体对称指数(LSI)将参与者分为高四头肌(HQ)组(LSI≥90%;n=18)和低四头肌(LQ)组(LSI<90%;n=8)。膝盖,臀部,和脚踝伸展力矩(相对于体重和支撑力矩[膝盖的总和,臀部,和脚踝力矩])和使用3维运动分析分析了双腿下蹲过程中的垂直地面反作用力。使用双向方差分析和单变量回归分析来测试股四头肌强度和生物力学变量的关联。
■发现峰值膝关节伸展力矩以及膝关节和髋关节伸展力矩与支撑力矩之比存在明显的逐肢交互作用(分别为P<.001,P=.015和P<.001)。与未受累肢体相比,LQ组的峰值膝关节伸展力矩和膝关节与支撑力矩之比明显较小,但受累肢体的髋关节与支撑力矩之比较大(95%CIs:膝关节伸展力矩,-0.273至-0.088N·m/kg;膝盖与支撑力矩比,-10.7%至-2.2%;髋部与支撑力矩比,3.2%至8.5%)。HQ组未发现肢体间差异。股四头肌强度的LSI与膝关节伸展力矩峰值的LSI显著相关(R2=0.183),膝盖与支撑力矩比(R2=0.256),和髋部与支撑力矩比(R2=0.233)。LQ组患肢下蹲时的平均最大等速股四头肌强度和最大膝关节伸展力矩分别为2.40±0.39和0.90±0.16N·m/kg,分别。
■双腿下蹲过程中的不对称生物力学与ACLR后持续的股四头肌无力相关。LQ组在下蹲期间减少了相关侧的膝盖伸肌力矩,尽管负载约为最大强度的一半。
■股四头肌加强锻炼,以及改善神经肌肉控制的干预措施,可能会降低双腿下蹲时的不对称生物力学。
UNASSIGNED: Although double-leg squatting is less dynamic and places less demand on the quadriceps compared with landing tasks, the relationship between double-leg squatting biomechanics and persistent quadriceps weakness after anterior cruciate ligament reconstruction (ACLR) is unknown.
UNASSIGNED: To clarify the relationships between asymmetries in quadriceps strength and lower limb biomechanics during double-leg squatting >1 year after ACLR.
UNASSIGNED: Controlled laboratory study.
UNASSIGNED: A total of 26 participants (5.5 ± 3.8 years after ACLR) were enrolled. The limb symmetry index (LSI) of isokinetic quadriceps strength was used to divide participants into the high-quadriceps (HQ) group (LSI ≥90%; n = 18) and the low-quadriceps (LQ) group (LSI <90%; n = 8). The knee, hip, and ankle extension moment (relative to body weight and support moment [sum of knee, hip, and ankle moments]) and vertical ground-reaction force during double-leg squatting were analyzed using 3-dimensional motion analysis. The association of quadriceps strength and biomechanical variables was tested using 2-way analysis of variance and univariate regression analysis.
UNASSIGNED: A significant group-by-limb interaction was found for the peak knee extension moment and the ratios of knee and hip extension moment to support moment (P < .001, P = .015 and P < .001, respectively). The LQ group showed a significantly smaller peak knee extension moment and knee to support moment ratio but a larger hip to support moment ratio in the involved limb than in the uninvolved limb (95% CIs: knee extension moment, -0.273 to -0.088 N·m/kg; knee to support moment ratio, -10.7% to -2.2%; hip to support moment ratio, 3.2% to 8.5%). No interlimb difference was found for the HQ group. The LSI of quadriceps strength was significantly associated with the LSI of peak knee extension moment (R2 = 0.183), knee to support moment ratio (R2 = 0.256), and hip to support moment ratio (R2 = 0.233). The mean maximum isokinetic quadriceps strength and peak knee extension moment during squatting on the involved limb of the LQ group were 2.40 ± 0.39 and 0.90 ± 0.16 N·m/kg, respectively.
UNASSIGNED: Asymmetrical biomechanics during double-leg squatting was associated with persistent quadriceps weakness after ACLR. The LQ group had reduced knee extensor moment on the involved side during squatting despite loading at approximately half the maximum strength.
UNASSIGNED: Quadriceps strengthening exercises, together with interventions to improve neuromuscular control, may reduce asymmetrical biomechanics during double-leg squatting.