CAFFEINE, PERFORMANCE, AND METABOLISM DURING REPEATED WINGATE EXERCISE TESTS

Investigations examining the ergogenic and metabolic influence of caff eine during short-term high-intensity exercise are few in number and h ave produced inconsistent results. This study examined the effects of caffeine on repeated bouts of high-intensity exercise in recreationall y active men. Subjects (n = 9) completed four 30-s Wingate (WG) sprint s with 4 min of rest between each exercise bout on two separate occasi ons. One hour before exercise, either placebo (Pl; dextrose) or caffei ne (Caf; 6 mg/kg) capsules were ingested. Caf ingestion did not have a ny effect on power output (peak or average) in the first two WG tests and had a negative effect in the latter two exercise bouts. Plasma epi nephrine concentration was significantly increased 60 min after Oaf in gestion compared with Pl; however, this treatment effect disappeared o nce exercise began. Caf ingestion had no significant effect on blood l actate, Oz consumption, or aerobic contribution at any time during the protocol. After the second Wingate test, plasma NH3 concentration inc reased significantly from the previous WG test and was significantly h igher in the Caf trial compared with Pl. These data demonstrate no erg ogenic effect of caffeine on power output during repeated bouts of sho rt-term, intense exercise. Furthermore, there was no indication of inc reased anaerobic metabolism after Caf ingestion with the exception of an increase in NH3 concentration.