Caffeine and muscle contraction:
Caffeine was found to increase short duration muscle contraction and muscle fiber conduction velocity in 14 male volunteers in a double-blind study using placebo or caffeine (6mg per kilogram). Measure of muscular function such as maximal voluntary isometric contractions, evoked maximal twitch, and maximal isokinetic contractions during elbow flexion were assessed. Mechanical and electromyographic signals from the biceps brachi muscles were recorded, and changes in the muscle-force velocity relationship and muscle fiber were evaluated. The toque-angular velocity curve improved after caffeine supplementation with an 8.7% increase in muscle conduction velocity. Caffeine was believed to improve motor unit muscle recruitment. (10)