Effect of muscular strengthening with electrical stimulation on sit-to-stand motion in young and elderly persons

The ability to get up from a chair is an important component in maintaining independence for elderly persons and for individuals with disabilities. The main aim of this work is to investigate the effect of muscular strengthening on sit-to-stand (STS) movement to get round the muscular weakness that often occur in elderly people. The sit-to-stand movement of 18 young persons and 10 elderly healthy subjects were acquired before and after an electrical stimulation (ES) strengthening cycle. Experimental data collected by using an optoelectronic system (ELITE), an EMG telemetric equipment and a force platform were analyzed by using a biomechanical planar model. The rising strategies and hip knee and ankle joint torques in the two different groups were calculated before and after ES cycle. The results showed that before ES the subjects, both young and elderly, used a strategy characterized by a fully trunk flexion in order to minimize the knee joint torque. After ES cycle we observed a diminished trunk flexion subsequent to the lower limb muscular strengthening. These data give a biomechanical analysis of the importance of joint torques strengths and postural stability in STS task and should be used to study the risk of falls in elderly.