Influence of two levels of caffeine on maximal torque at selected angular velocities.

The purpose of this study was to determine the effect of two doses of caffeine on peak torque and muscle endurance in the knee extensors and flexors. Twenty males and 16 females were randomly assigned to one of three groups: 600 mg caffeine, 300 mg caffeine, or a control receiving a placebo. Subjects with similar caffeine consumption history were used and all subjects abstained from caffeine usage for 24 hours prior to testing. Subjects were tested for maximal strength and endurance at 75, 180, and 300 degrees per second using a Cybex II Isokinetic Dynomometer interfaced with a Cybex Data Reduction Computer. After pretesting, each subject was given one of three solutions using a double-blind design. Following a one hour rest and absorption period, the subjects were again tested. Data were analyzed using a 3 x 2 repeated measures analysis of variance with a grouping factor at three levels (600 mg vs 300 mg vs 0 mg) and a trial factor at two levels (pre- vs posttest). The following variables were analyzed at all angular velocities: peak torque and subsequent joint angle, peak torque at 30 degrees, and peak torque at 70 degrees. At 300 degrees per second, the dependent variables were total torque for 15 repetitions, total torque for the first 3 repetitions, and total torque for the last 3 repetitions. The results indicated no significant changes from pre- to posttest. It was concluded that maximal strength and endurance was not affected by the two levels of caffeine used in this study and that caffeine may not be considered an ergogenic aid in strength output in subjects naive to resistance training.