The impact of whole-hand vibration exposure on the sense of angular position about the wrist joint.

Objectives: The purpose of this research is to determine the impact of whole-hand vibration on the capacity of subjects to identify previously presented positions of the hand in both wrist flexion and extension.

Methods: In each movement direction, targets of 15 or 30 degrees were presented with an imposed passive movement from the start position. During the second imposed movement, subjects were required to identify when the target position had been reached.

Summation of forces from multiple motor units in the cat soleus muscle.

Nearly all muscle models and most motor control concepts assume that forces from individual muscle fibers and motor units sum in an additive manner once effects of in-series tendon compliance are taken into account. Due to the numerous mechanical linkages between individual fibers, though, it is unclear whether this assumption is warranted. This work examined motor unit force summation over a wide range of muscle forces in the cat soleus.