A novel method of inducing muscle cramps using repetitive magnetic stimulation

The lack of a practical model has hampered attempts to study the pathophysi ology of muscle cramps. We investigated the feasibility, efficacy, and repr oducibility of repetitive magnetic stimulation in producing experimental cr amps, in 14 healthy subjects, the tibial nerve at the ankle was stimulated with a magnetic stimulator at rates beginning at 4 Hz to a maximum of 20 Hz . The frequency was gradually increased until a cramp was produced. Ten of 14 subjects demonstrated a muscle cramp. All subjects rated the discomfort of the procedure to be mild or moderate. Repeat testing yielded values that were highly reproducible. This technique holds promise for clinical studie s and therapeutic trials. (C) 2000 John Wiley & Sons, Inc.