Comparison of the pedalling performance induced by magnetic and electrical stimulation cycle ergometry in able-bodied subjects

The purpose of the study was to compare the mechanical power and work generated by able-bodied subjects during functional magnetic stimulation (FMS) vs. functional electrical stimulation (FES) induced ergometer training conditions. Both stimulation methods were applied at a 30 Hz frequency to the quadriceps muscles of 22 healthy able-bodied subjects to induce cycling for 4× four minutes or until exhaustion. FMS was performed via large surface, cooled coils, while FES was applied with a typical stimulation setup used for cycling. Significantly more (p < 10−3) muscular power was generated by FMS (23.8 ± 9.1 W [mean ± SD]) than by FES (11.3 ± 11.3 W). Additionally, significantly more (p < 10−6) work was produced by FMS than by FES (4.413 ± 2.209 kJ vs. 0.974 ± 1.269 kJ). The increase in the work was paralleled by a significant prolongation of time to cycling failure (181.8 ± 33.4 s vs. 87.0 ± 54.0 s, respectively, p < 10−5). Compared to FES, FMS can produce more intense and longer cycling exercise in able-bodied subjects. The differing dynamic behaviour of FMS and FES in the presented measurement setup might be related to stimulation induced pain and fatigue mechanisms of the neuromuscular system.