Caffeine improves strength gains in response to 6 weeks of resistance training

Caffeine has become an increasingly popular supplement in recent years since its removal from the World Anti-Doping Agency banned substance list in 2004 (15). While the benefits of caffeine on aerobic exercise are well described (8,10), fewer studies have investigated the effect of caffeine on anaerobic performance. A recent meta-analysis revealed that, of the studies examined, over 80% reported a positive effect of caffeine on maximal voluntary contraction strength and muscular endurance (13). Similarly, caffeine appears to have an ergogenic effect on sprint and power based performances, although the mechanisms underlying these effects remain unknown (2).

To date, the majority of studies of anaerobic performance have only investigated the acute response to caffeine ingestion. The potential benefits of longer term caffeine supplementation have yet to be examined. With respect to resistance training, anecdotal evidence suggests that athletes use caffeine to assist their training performance (8). However, no empirical data exist to confirm whether caffeine supplementation improves strength gains in response to a resistance training program. Therefore, the purpose of this study was to determine whether moderate doses of caffeine before resistance training sessions increase strength gains after a six-week program.