Abstract

Computerized testing of 20 élite male athletes was performed to determine the effect of 7 mg kg-1 caffeine on strength and power of the knee extensors and flexors. Subjects received counterbalanced administrations of either caffeine or a placebo on two separate occasions. Peak torque (T) was measured for knee extension (ET) and flexion (FT) at angular velocities of 30 degrees, 150 degrees and 300 degrees s-1. Additionally, performance for the first 125 ms (TAE) and power (W) were recorded during 300 degrees s-1. Testing sessions were held 1 week apart, at which time the placebo/caffeine administration was reversed. A 2 x 2 repeated measures analysis of variance supplemented with a Neuman-Keuls post hoc test showed the following--significant caffeine-related increases (P < 0.05) for ET at 30 degrees s-1, ET at 300 degrees s-1, and ETAE, and EW at 300 degrees s-1. Dependent t-tests performed for pre- to post-test means showed significant changes for the caffeine group in ET at 30 degrees s-1, FT at 30 degrees s-1, FT at 150 degrees s-1, ET at 300 degrees s-1, FT at 300 degrees s-1, E and FTAE, and EW at 300 degrees s-1. No significant effects were found for the placebo trial in any variable. It was concluded that caffeine can favourably affect some strength parameters in highly resistance-trained males. However, differences in subject fibre type, motivation and caffeine sensitivity need to be elucidated.