PAIN, M.T.G. and CHALLIS, J.H., 2002. Soft tissue motion during impacts: their potential contributions to energy dissipation. Journal of Applied Biomechanics 18 (3), pp. 231-242.
The aims of this study were to quantify intra-segmental motion using an array of 28 surface
mounted markers to examine frequency and amplitude measurements of the intra-segmental
motion to calculate forces and energy transfer; and to show that the underlying muscles are a
major contributor to the skin marker motion. One subject performed 27 trials under three
conditions in which his forearm was struck against a solid object fixed to a force plate while the
locations of the markers were recorded at 240 Hz. For impacts with equal peak forces the muscle
tension significantly affected the amount of intra-segmental motion. Tensing the arm reduced the
intra-segmental motion by 50 %. The quadrilateral sectors defined by the markers changed in area
by 11% with approximately equal motion in the vertical and horizontal direction. The maximum
linear marker motion was 1.7 cm. The intra-segmental motion had distinct frequency components
around 14 and 20 Hz. Soft tissue deformation could account for 70 % of the energy lost from the
forearm during these impacts. The study has demonstrated the important role that intra-segment
soft tissue motion can have on the kinetics of an impact.