Department of Mechanical, University of Michigan, Ann Arbor, MI 48109, USA.
J Exp Biol. 2010 Dec 15;213(Pt 24):4257-64. doi: 10.1242/jeb.044297.
The muscles and tendons of the lower extremity are generally considered the dominant producers of positive and negative work during gait. However, soft-tissue deformations not captured by joint rotations might also dissipate, store and even return substantial energy to the body. A key locomotion event is the collision of the leg with the ground, which deforms soft tissues appreciably in running. Significant deformation might also result from the impulsive ground collision in walking. In a study of normal human walking (N=10; 0.7-2.0 m s(-1) speeds), we show indirect evidence for both negative and positive work performed by soft tissue, consistent with a damped elastic collision and rebound. We used the difference between measured joint work and another quantity - the work performed on the body center of mass - to indicate possible work performed by soft tissue. At 1.25 m s(-1), we estimated that soft tissue performs approximately 7.5 J of negative work per collision. This constitutes approximately 60% of the total negative collision work and 31% of the total negative work per stride. The amount of soft tissue work during collision increases sharply with speed. Each collision is followed by 4 J of soft tissue rebound that is also not captured by joint work measures. Soft tissue deformation may save muscles the effort of actively dissipating energy, and soft tissue elastic rebound could save up to 14% of the total positive work per stride. Soft tissues not only cushion impacts but also appear to perform substantial work.
下肢的肌肉和肌腱通常被认为是步态中产生正功和负功的主要来源。然而，关节旋转未捕捉到的软组织变形也可能耗散、储存甚至向身体返回大量能量。一个关键的运动事件是腿部与地面的碰撞，在跑步中，这会使软组织明显变形。在行走时，地面的冲击也可能导致显著的变形。在一项对正常人类行走的研究（N=10；速度为 0.7-2.0 m s(-1)）中，我们间接证明了软组织的负功和正功，这与阻尼弹性碰撞和回弹一致。我们使用测量关节功与另一个量（质心的身体功）之间的差异来表示软组织可能做的功。在 1.25 m s(-1)时，我们估计软组织在每次碰撞中大约做了 7.5 J 的负功。这大约占总负碰撞功的 60%和总每步负功的 31%。碰撞过程中软组织功的量随速度急剧增加。每次碰撞后，软组织的回弹会产生 4 J 的能量，这也未被关节功测量所捕捉到。软组织的变形可能使肌肉无需主动耗散能量，而软组织的弹性回弹可以节省每步总正功的 14%。软组织不仅起到了缓冲冲击的作用，而且似乎还做了大量的功。
