EFFECT OF CAFFEINE INGESTION ON TORQUE AND MUSCLE ACTIVITY DURING RESISTANCE EXERCISE IN MEN

Introduction: We examined the effect of caffeine ingestion on muscle torque production and muscle activity at different contraction speeds in trained men. Methods: 10 men (mean age +/- SD = 22 +/- 1.1 years) volunteered to participate. A double-blind, randomized cross-over design was used. Sixty minutes postingestion of caffeine (6 mg kg(-1)) or placebo, participants completed 6 repetitions of isokientic knee extension at 3 angular velocities (30 degrees s(-1), 150 degrees s(-1), 300 degrees s(-1)) from which peak torque was determined. Electromyographic activity of the vastus medialis was also collected. Results: Repeated measures analysis of variance indicated that muscle torque production was significantly higher (P=0.02) with caffeine compared with placebo. A significant (P=0.02) substance by velocity interaction for muscle activity indicated significantly higher vastus medialis muscle activity in the presence of caffeine versus placebo, and this difference was amplified as angular velocity increased. Conclusions: Acute caffeine ingestion improves muscle performance and increases muscle activity during short-duration maximal dynamic contractions.