Effect Of Caffeine On Muscular Strength And Endurance In Resistance-trained College-aged Males

Abstract

PURPOSE: To determine if pre-exercise caffeine consumption would significantly enhance performance during muscular strength and endurance testing in habitual caffeine users. METHODS: Males (n=8, 22.12±.83yrs., 85.82±12.75kg) who self-reported to be habitual caffeine users volunteered for the study. All participants reported resistance training a minimum of 3 times per week for at least 3 months prior to involvement in the study. Participants abstained from caffeine for at least 48 hours prior to testing. In this double-blind, placebo-controlled, within-subjects design, participants were randomly assigned to consume either 150mg caffeine (10 oz. standardized coffee) or decaffeinated coffee (10 oz. placebo) and performed a 5-repetition (5RM) maximal effort leg press followed by a maximal effort YMCA push-up test. Participants returned 1 week after the first trial for the second treatment. A paired samples t-test was performed to test for significant differences between treatments. RESULTS: Analysis showed significant increases in 5RM leg press weight (p=0.029) and push up performance (p=0.009) between treatment and placebo trials. An 11% improvement was seen in 5RM leg press weight (600±161 lbs) compared to the placebo (539±135 lbs). Similarly, there was a 14% improvement in push up performance (caffeine 40±10 repetitions, placebo 35±7 repetitions) between treatment and placebo testing. The relative dose of caffeine for the participants was 1.78±0.26 ml/kg of bodyweight (1.4 - 2.2 mg/kg of bodyweight). CONCLUSIONS: Our results indicate that 150mg caffeine may improve muscular strength and endurance in resistance-trained habitual caffeine users. Further, the relative amount of caffeine consumed was less than that believed to be required for an ergogenic effect on performance. These results suggest that for habitual caffeine users that follow a washout period, a lower caffeine dosage can still elicit an ergogenic effect on muscular strength and endurance. Future research should determine whether our results are consistent across both sexes as well as determine whether the same ergogenic effect can be seen following similar dosages to those who are not habitual users.