Isometric muscle force response of the human lower limb.

This paper deals with isometric muscle force response of the human lower limb when the leg is subjected to various external forces applied on the knee and ankle joints. The major components of the research apparatus are a subject restraint system, a force application device which employs three sonic emitters, and an upper leg cuff with four sonic emitters. The sonic emitters are used to determine the direction and the location of the force application on the lower limb and the orientation of the upper leg with respect to the torso. The numerical results are presented from experiments conducted on three male and three female subjects to determine their isometric muscle resistance against external forces trying to dislodge their lower limbs from several initial configurations. Quantitative results on the isometric muscle force capability of the subjects, when their lower limbs are dislodged from the initial stowed position, are also presented. It is concluded that, although there are intra- and inter-subject variations for the maximum values of the resistive muscle forces of the lower limb, there are some trends in the behavior of their magnitudes. Incorporating the results of the present research into multi-segmented models of the human body should improve the long-time response capabilities of these models so that they can simulate more realistically the biodynamic events which take place when the human body is subjected to high magnitudes of external forces lasting more than a fraction of a second.