2009 Volume 47 Issue 1 Pages 57-63
In order to study the availability of pulsed magnetic stimulation (pMS) for recovery of acute muscle fatigue, evoked potential were recorded from soleus (slow-twitch fiber type, fatigue-resistant) and extensor digitorum longus (fast-twitch fiber type, fatigue-sensitive) using hypokalemic and normal Wistar rats in vivo. Hypokalemic rats are useful as nerve-muscle disease model. These rats are suffering from hypokalemic periodic paralysis. Muscle fatigue was caused by electric stimulation to the sciatic nerve for 3 min. pMS were delivered every 2 min for 30 s over the lower limb after induced muscle fatigue. pMS were controlled by a Magnetic stimulator with a figure-of-eight coil (Magstim 200, The Magstim Company, UK) . The coil was placed in order to induce a muscle twitch. It was found that a recovery curve in evoked potential for the muscle varied depending on two factors: the type of muscle fibers and the hypokalemic condition. In addition, the recovery curve in evoked potential was improved slightly by pMS. These findings suggest that recovery curves in evoked potential may reflect characteristics of muscle fiber type and hypokalemia, and that pMS may have an effect on recovery of muscle fatigue.
