Analysis of upper limb smoothness differences between elderly and young subjects during reaching exercises while moving in a velocity dependent force field

Abstract

The inactivity of the ACL was due to the characteristic of both motor tasks [3]. Regarding the PCL, the higher repeatability obtained during the SUP_EXT (Fig. 1a), was probably due to a major activity of the extensor muscles generating motion against gravity. During the SUP_FLEX the eccentric contraction of the extensor muscles, needed to break the movement in favour of gravity, was less controlled and a minor repeatability was obtained (Fig. 1b). In CSR smaller forces were calculated with respect to those obtained in the SUP. This can be explained considering the characteristics of the motor task: using two legs, smaller stabilization contribution was required to each ligament, in particular in the M/L direction. In conclusion, the devised model was effective in evaluating loads in the ACL and PCL during the execution of daily living activities.