Background: Some examples are presented to show how superimposed electrical stimulation of muscles during maximum voluntary effort can be used to enable subjects to achieve greater joint torque, rate of joint torque development, and the joint angular velocity as when performing only voluntarily with maximum effort.
Participants: Ten students of physical education not involved into a regular sport training participated the study.
Interventions: The subjects performed isometric and concentric knee extensions and squat jumps, without and with superimposed electrical stimulation of the quadriceps muscles.
Measures: A knee torque and angular displacement were observed during isometric and concentric knee extension. During the jumping, a vertical component of the ground reaction force was measured.
Results: Results showed that the maximal knee torque, as well as a torque rise, were higher in isometric knee extension trials with superimposed electrical stimulation. The same was observed in concentric knee extensions, where greater knee torque during superimposed electrical stimulation also resulted in higher angular velocity and a more extended knee at the end of the movement. In squat jumps, the application of the superimposed electrical stimulation resulted in poorer performance.
Conclusions: It was concluded that superimposed electrical stimulation was effective in some simple motor tasks, but not in more complex tasks where a co-ordination of multiple muscles of different groups was necessary for improved performance.