Department of Kinesiology, California State University, Fullerton, CA.
Department of Kinesiology, Utah State University, Logan, UT.
Med Sci Sports Exerc. 2019 May;51(5):951-961. doi: 10.1249/MSS.0000000000001891.
Obesity influences gait and muscle function, which may contribute to knee osteoarthritis. This study aimed 1) to compare gait biomechanics and quadriceps function between individuals with and without obesity and 2) to examine the association between quadriceps function and gait biomechanics.
Forty-eight individuals with and 48 without obesity participated and were matched on age and sex. Gait biomechanics at standardized and self-selected speeds were used to assess peak vertical ground reaction force (vGRF), vertical loading rate (vLR), internal knee extension moment (KEM), peak knee flexion angle (KFA), knee flexion excursion (KFE), and knee joint stiffness. Quadriceps function was assessed using peak isometric strength (peak torque), early (RTD100) and late (RTD200) rate of torque development (RTD), and vastus lateralis cross-sectional area (CSA) and echo intensity (EI).
When normalized to fat-free mass, individuals with obesity had lower RTD100 (P = 0.04) and RTD200 (P = 0.02) but higher vastus lateralis CSA (P < 0.01) and EI (P < 0.01) compared with normal weight controls. The group-speed interaction was significant for normalized vGRF (P < 0.01), normalized vLR (P = 0.02), normalized KEM (P = 0.03), and normalized knee joint stiffness (P = 0.02). Post hoc analyses indicate a smaller normalized vGRF and normalized KEM, and lower knee joint stiffness in individuals with obesity compared with normal weight controls at self-selected speed. There were main effects of speed for all kinematic and kinetic variables, and body mass index group for all absolute kinetic variables as well as normalized vGRF (all P < 0.001). A lower vastus lateralis EI (P = 0.04) and greater RTD100 (P < 0.01) were associated with a larger KEM in individuals with obesity.
Individuals with obesity have quadriceps dysfunction that is weakly associated with KEM during walking. Exercise interventions that improve quadriceps function may improve walking mechanics.
肥胖会影响步态和肌肉功能，这可能导致膝关节骨关节炎。本研究旨在：1）比较肥胖者和非肥胖者的步态生物力学和股四头肌功能；2）探讨股四头肌功能与步态生物力学的关系。
48 名肥胖者和 48 名非肥胖者参与了研究，他们在年龄和性别上相匹配。采用标准和自选速度下的步态生物力学评估峰值垂直地面反力（vGRF）、垂直加载率（vLR）、膝关节内伸肌力矩（KEM）、峰值膝关节屈曲角度（KFA）、膝关节屈曲范围（KFE）和膝关节刚度。股四头肌功能采用峰值等长力量（峰值扭矩）、早期（RTD100）和晚期（RTD200）扭矩发展率（RTD）以及股外侧肌横截面积（CSA）和回声强度（EI）评估。
当按去脂体重标准化时，肥胖者的 RTD100（P = 0.04）和 RTD200（P = 0.02）较低，但股外侧肌 CSA（P < 0.01）和 EI（P < 0.01）较高。组间速度的交互作用对标准化 vGRF（P < 0.01）、标准化 vLR（P = 0.02）、标准化 KEM（P = 0.03）和标准化膝关节刚度（P = 0.02）有显著影响。事后分析表明，与正常体重对照组相比，肥胖者在自选速度下的标准化 vGRF 和标准化 KEM 较小，膝关节刚度较低。所有运动学和动力学变量以及身体质量指数组的速度均有主要影响，所有绝对动力学变量以及标准化 vGRF 也均有体重指数组的主要影响（均 P < 0.001）。肥胖者的股外侧肌 EI 较低（P = 0.04）和 RTD100 较高（P < 0.01）与 KEM 较大相关。
肥胖者的股四头肌功能障碍与步行时的 KEM 呈弱相关。改善股四头肌功能的运动干预可能改善步行力学。
