Caffeine improves neuromuscular function during maximal dynamic exercise

Abstract

In this study we tested the hypothesis that caffeine supplementation improves neuromuscular function, which has both nutritional and clinical relevance. Fourteen male subjects (mean ± SD: 23.8 ± 2.8 years) volunteered in a double-blind, repeated-measures study with placebo (PLA) or caffeine (CAFF) (6 mg kg(-1)). Maximal voluntary isometric contractions (MVCs), evoked maximal twitch, and maximal isokinetic contractions during elbow flexion were assessed. Mechanical and electromyographic (EMG) signals from the biceps brachii muscle were recorded, and muscle fiber conduction velocity (CV) was calculated to evaluate changes in the muscle force-velocity relationship and muscle fiber recruitment. The torque-angular velocity curve was enhanced after CAFF supplementation. This was supported by a concomitant increase of CV values (8.7% higher in CAFF). Caffeine improves muscle performance during short-duration maximal dynamic contractions. The concomitant improvement of mean fiber CV supports the hypothesis of an effect of caffeine on motor unit recruitment.