Department of Rehabilitation Sciences, University of Kentucky, Lexington, KY, USA.
Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, KY, USA.
J Biomech. 2014 Jan 3;47(1):32-8. doi: 10.1016/j.jbiomech.2013.10.026. Epub 2013 Oct 22.
When the foot impacts the ground in running, large forces and loading rates can arise that may contribute to the development of overuse injuries. Investigating which biomechanical factors contribute to these impact loads and loading rates in running could assist clinicians in developing strategies to reduce these loads. Therefore, the goals of our work were to determine variables that predict the magnitude of the impact peak and loading rate during running, as well as to investigate how modulation of knee and hip muscle activity affects these variables. Instrumented gait analysis was conducted on 48 healthy subjects running at 3.3m/s on a treadmill. The top four predictors of loading rate and impact peak were determined using a stepwise multiple linear regression model. Forward dynamics was performed using a whole body musculoskeletal model to determine how increased muscle activity of the knee flexors, knee extensors, hip flexors, and hip extensors during swing altered the predictors of loading rate and impact peak. A smaller impact peak was associated with a larger downward acceleration of the foot, a higher positioned foot, and a decreased downward velocity of the shank at mid-swing while a lower loading rate was associated with a higher positioned thigh at mid-swing. Our results suggest that an alternative to forefoot striking may be increased hip flexor activity during swing to alter these mid-swing kinematics and ultimately decrease the leg's velocity at landing. The decreased velocity would decrease the downward momentum of the leg and hence require a smaller force at impact.
当脚在跑步时着地时，可能会产生较大的力和加载率，这可能导致过度使用损伤的发生。研究哪些生物力学因素会导致跑步时的这些冲击载荷和加载率，可能有助于临床医生制定降低这些载荷的策略。因此，我们的工作目标是确定可预测跑步时冲击峰值和加载率大小的变量，并研究膝关节和髋关节肌肉活动的调节如何影响这些变量。对 48 名健康受试者在跑步机上以 3.3m/s 的速度进行了仪器步态分析。使用逐步多元线性回归模型确定了加载率和冲击峰值的前四个预测因子。使用全身肌肉骨骼模型进行了正向动力学分析，以确定摆动过程中膝关节屈肌、膝关节伸肌、髋关节屈肌和髋关节伸肌的肌肉活动增加如何改变加载率和冲击峰值的预测因子。较小的冲击峰值与脚的向下加速度较大、脚的位置较高以及小腿在中间摆动时的向下速度降低有关，而较低的加载率与中间摆动时大腿的位置较高有关。我们的研究结果表明，前脚掌着地的替代方法可能是增加摆动过程中的髋关节屈肌活动，以改变这些中间摆动运动学，最终降低腿部在着陆时的速度。速度的降低会降低腿部的向下动量，因此在冲击时需要较小的力。
