A promising approach to prevent skeletal muscle cramps

Skeletal muscle cramps are a sudden, involuntary, and painful contractions of the muscle or part of it. Though this phenomenon is known from time immemorial and its life-time prevalence among healthy subjects is high, there is still a lack of sufficient prevention strategies. In the framework of five sub-projects we investigated the effect of electrically induced muscle cramps (EIMCs) on the individual cramp threshold frequency (CTF) and if EIMCs are able to reduce the incidence of muscle cramps in cramp patients.

In all sub-projects, three sets of EIMCs were induced in calf muscles by stimulating the muscles in a maximally shortened position at a frequency that was 30 Hz above the individual CTF. Each set consisted of 6x5 s wave pulsed currents, separated by 10 s breaks.

The sub-projects revealed that the CTF was markedly increased after 12, 6, or 4 cramp training sessions. Furthermore, it was observed that the CTF remained increased over three weeks and that this training induced a calf muscle hypertrophy despite the fact that calf muscles were unable to produce high muscle tension (an important anabolic signal) in the maximally shortened position. Since the cramp training did not negatively affect muscle performance, it may also be recommended to athletes, who suffer from exercise associated muscle cramps. Finally, it turned out from one sub-project that incidence of muscle cramps was markedly reduced in cramp patients. In summary, EIMCs seem to provide a promising new approach to prevent muscle cramps.