Acute specific effects of caffeine-containing energy drink on different physical performances in resistance-trained men

Abstract

Caffeine containing energy drink (ED) is frequently used as ergogenic aid, but its effect on performance need more investigation. Thus, the aim of this study was to analyze the effects of acute ingestion of an ED on the physical performance of resistance-trained men subjected to successive tests in the same experimental protocol. Fifteen resistance-trained males (21.0 ± 0.3 yrs; 177.4 ± 1.8 cm; 79.6 ± 1.8 kg) ingested 2.5 mg caffeine per kg of body weight (619.5 ± 14.6 mL of ED) or a placebo in a double-blind randomized cross-over design. Physical performance was randomized for the maximum repetition tests (80% 1RM) in the bench press exercise and unilateral knee extension (dominant leg), maximal isometric hand-grip test in both hands, standing long jump and repeated sprint ability test. The paired Student-t test showed that ED intake increased performance compared to the placebo for the number of repetitions in the unilateral knee extension test of the dominant leg (11.5 ± 0.9 reps vs 9.5 ± 0.8 reps; P = 0.001) and bench press (10.2 ± 0.4 reps vs 8.1 ± 0.5 reps; P = 0.01); and also increased isometric strength in the hand-grip maximal test in the right (53.7 ± 1.5 kg vs. 47.7 ± 1.6 kg; P = 0.02) and left hand (52.9 ± 1.5 kg vs. 45.9 ± 1.3 kg; P = 0.02). In conclusion, acute ingestion of ED increased performance only in specific strength tests in resistance-trained men.