Increased post-exercise facilitation of motor evoked potentials in multiple sclerosis

Objectives: To study post-exercise facilitation following a non-fatigue exercise in a homogenous group of multiple sclerosis (MS) patients with complaints of muscle fatigue. Methods: In 15 MS patients and matched controls motor evoked potentials (MEP) were recorded from the biceps brachii muscle at time delays of 0.5–30 s after an isometric contraction with a torque of 50% of maximal voluntary contraction (MVC) maintained for 2–6 s. In addition, MEP was recorded after isometric torque of 25, 50, and 100% of MVC maintained for 6 s. Results: Isometric non-fatigue contraction induced significant post-exercise increase in MEP amplitude in MS patients compared with controls being most pronounced after a contraction for 6 s. The post-exercise increase in MEP lasted for longer than 30 s in MS patients. Conclusions: Post-exercise increase of MEP amplitude following a non-fatigue exercise was significant in MS patients with complaints of muscle fatigue compared with healthy subjects.