Forskning

July 30, 2014

Acute effects of caffeine on strength and muscle activation of elbow flexors

M A Trevino et al, 2014, Acute effects of caffeine on strength and muscle activation of elbow flexors. Journal of Strength and Conditioning Research, published online ahead of print.

Human Study – Physical Performance

ABSTRACT: The purpose of this study was to examine the effects of caffeine on strength and muscle activation of the elbow flexors. Thirteen recreationally active male volunteers (mean ± SD, age: 21.38 ± 1.26 years) came to the laboratory four times. Visit one served as a familiarization visit. During visits two through four, subjects ingested a randomly assigned drink, with or without caffeine (0, 5, or 10 mg∙kg of body mass), and performed three maximal isometric muscle actions of the elbow flexors sixty minutes after ingestion. Maximal strength and rate of torque development (RTD) were recorded. Electromyographic (EMG) and mechanomyographic (MMG) amplitude and frequency, and electromechanical delay (EMD) and phonomechanical delay (PMD) were measured from the biceps brachii. The results indicated that the ingestion of 0 (placebo), 5 or 10 mg∙kg of body mass of caffeine did not significantly influence (P > 0.05) peak torque, RTD, normalized EMG amplitude or frequency, normalized MMG amplitude, or EMD and PMD. Normalized MMG frequency was significantly lower (P < 0.05) following ingestion of five mg∙kg of body mass of caffeine compared to the placebo trial. This was most likely an isolated finding as MMG frequency was the only variable to have a significant difference across all trials. The results suggested that ingestion of either five or ten mg∙kg of body mass of caffeine does not provide an ergogenic effect for the elbow flexors during isometric muscle actions.