Department of Mechanical Engineering, Stanford University, Stanford, CA, United States.
Department of Bioengineering, Stanford University, Stanford, CA, United States.
Sci Rep. 2020 Apr 3;10(1):5872. doi: 10.1038/s41598-020-62464-3.
Running is thought to be an efficient gait due, in part, to the behavior of the plantar flexor muscles and elastic energy storage in the Achilles tendon. Although plantar flexor muscle mechanics and Achilles tendon energy storage have been explored during rearfoot striking, they have not been fully characterized during forefoot striking. This study examined how plantar flexor muscle-tendon mechanics during running differs between rearfoot and forefoot striking. We used musculoskeletal simulations, driven by joint angles and electromyography recorded from runners using both rearfoot and forefoot striking running patterns, to characterize plantar flexor muscle-tendon mechanics. The simulations revealed that foot strike pattern affected the soleus and gastrocnemius differently. For the soleus, forefoot striking decreased tendon energy storage and fiber work done while the muscle fibers were shortening compared to rearfoot striking. For the gastrocnemius, forefoot striking increased muscle activation and fiber work done while the muscle fibers were lengthening compared to rearfoot striking. These changes in gastrocnemius mechanics suggest that runners planning to convert to forefoot striking might benefit from a progressive eccentric gastrocnemius strengthening program to avoid injury.
跑步被认为是一种高效的步态，部分原因是足底屈肌肌肉的行为和跟腱的弹性储能。虽然已经研究了后足着地时的足底屈肌力学和跟腱储能，但在前足着地时还没有完全描述。本研究探讨了跑步时后足和前足着地时足底屈肌-肌腱力学的差异。我们使用肌肉骨骼模拟，由记录跑步者的关节角度和肌电图驱动，使用后足和前足着地跑步模式来描述足底屈肌-肌腱力学。模拟结果表明，足着地模式会对比目鱼肌和腓肠肌产生不同的影响。对于比目鱼肌，与后足着地相比，前足着地会降低跟腱的储能和纤维做功，同时纤维缩短。对于腓肠肌，与后足着地相比，前足着地会增加肌肉激活和纤维做功，同时纤维伸长。腓肠肌力学的这些变化表明，计划转换为前足着地的跑步者可能受益于渐进的离心腓肠肌强化计划，以避免受伤。
