Mhe. Delussanet et Rm. Alexander, A SIMPLE-MODEL FOR FAST PLANAR ARM MOVEMENTS - OPTIMIZING MECHANICAL ACTIVATION AND MOMENT-ARMS OF UNIARTICULAR AND BIARTICULAR ARM MUSCLES, Journal of theoretical biology, 184(2), 1997, pp. 189-203
In this study a simple model of a two segmented arm with only two musc
les is used to study an underarm throw and an overarm stroke. There is
a uniarticular shoulder muscle and an elbow muscle with facultatively
an additional moment arm on the shoulder. The effect of changing the
shoulder moment of the latter muscle, and of changing its mechanical d
elay is measured. The effect of tendons is assessed, and of throwing o
r striking using heavy weights. Some of the trials are analysed in det
ail to answer the question why some results are better than others. Wi
th uniarticular muscles we always found a proximal-distal sequence in
muscle activity, but with a biarticular muscle sometimes this sequence
can be absent. Tendons and the weight that is held do influence the o
ptimal delay, but not the optimal moment arm. The model predicts a dif
ferent optimal technique for a stroke with a light or a heavy tool. (C
) 1997 Academic Press Limited.