Barry D T, Cole N M
Department of Physical Medicine and Rehabilitation, University of Michigan Medical Center, Ann Arbor 48109-0042.
Biophys J. 1988 Jun;53(6):899-905. doi: 10.1016/S0006-3495(88)83171-0.
The pressure field produced by an isometrically contracting frog gastrocnemius muscle is described by the fluid mechanics equations for a vibrating sphere. The equations predict a pressure amplitude that is proportional to the lateral acceleration of the muscle, inversely proportional to the square of the distance from the muscle, and cosinusoidally related to the major axis of lateral movement. The predictions are confirmed by experiments that measure the pressure amplitude distribution and by photographs of muscle movement during contraction. The lateral movement of muscle has the appearance of an oscillating system response to a step function input--the oscillation may be at the resonant frequency of the muscle and therefore may provide a means to measure muscle stiffness without actually touching the muscle.
等长收缩的青蛙腓肠肌产生的压力场由振动球体的流体力学方程描述。这些方程预测的压力幅值与肌肉的横向加速度成正比，与距肌肉距离的平方成反比，并且与横向运动的主轴呈余弦关系。通过测量压力幅值分布的实验以及收缩过程中肌肉运动的照片证实了这些预测。肌肉的横向运动表现为对阶跃函数输入的振荡系统响应——该振荡可能处于肌肉的共振频率，因此可能提供一种无需实际接触肌肉就能测量肌肉刚度的方法。
