[Functional magnetic stimulation as a supposedly 'painless' option for movement induction in plegics]

It is known in the rehabilitation of central pareses that functional electrical stimulation (FES) of the muscles can induce movement and accomplish training in patients. The main limitations of this method are that patients with preserved sensation experience pain and the reflexes triggered by FES. Therefore the application of the largely "painless" magnetic stimulation (FMS) of the muscles would be a potential alternative in the rehabilitation of patients with partially preserved sensation. As the generation of high force and power levels is considered to be an essential requirement of effective rehabilitation strategies, we have shown in previous work that FMS with large surface magnetic coils fitted to the thigh can generate about 2.5 times higher isometric forces in patients with preserved sensation, than can FES.

The goal of the present pilot study was to prove that the mechanical power generated by functional magnetic stimulation is superior to that produced by electrical stimulation too.

We have measured the mechanical torque, the power, the accomplished work and the kinematics in 4 healthy control subjects, who performed pedalling propelled by FMS and FES until complete muscular exhaustion, using a cycling test-bed under isotonic conditions (constant resistance).

We have proved that the generated work, mean power, cadence and smoothness of pedalling essentially depend on peak torque and power. Furthermore, we found evidence that smoother pedalling could be achieved using magnetic, compared to electrical stimulation because of the higher peak torques that were generated by FMS.

This study supports the concept that peripheral magnetic stimulation is an appropriate rehabilitation method for patients with central pareses and preserved sensory apparatus because FMS is less painful than electrical stimulation.