Caffeine intake improves muscular endurance and induces depletion of anaerobic work capacity in the bench press

Abstract

Aim: To investigate the effects of caffeine (CAF) ingestion on anaerobic work capacity (AWC) and muscular endurance in the bench press exercise at predictive intensities equivalent to 20, 25, and 30% of 1RM. Methods: Thirteen males (age: 23 ± 3 years; body mass 83.5 ± 4.9 kg; height 172.8 ± 5.0 cm and 1RM 82 ± 24 kg) had their 1RM test evaluated in the bench press exercise and the time until failure was performed at intensities equivalent to 20%, 25%, and 30% of 1RM to CAF (350mg) or placebo (PLA, cellulose). AWC was measured from the linear equation: "Force = Critical Force + (AWC x 1/timeout)". Results: CAF enhanced the time until failure at 20% of 1RM (PLA = 202.6 ± 29.1s; CAF = 243.2 ± 20.6s), but there was no ergogenic effect at 25% (PLA = 188.8 ± 23.5 s; CAF = 195.6 ± 27.1 s), and 30% (PLA = 147.4 ± 15.8 s; CAF = 145.4 ± 14.8 s). AWC in CAF was lower than PLA (PLA = 6378.0 ± 1214.9 J; CAF = 3246.4 ± 1389.7 J; p = 0.03; Effect size = 0.88). Critical Force (N) was not different between treatments PLA 29.97 ± 11.54% of 1RM and CAF 3.74 ± 3.69% of 1 RM (p=0.47; Effect size= 0.28). Conclusion: Acute CAF intake (350mg) reduces the AWC and increases the time until failure at 20% of 1 RM, but not Critical Force and muscular endurance at 25% and 30% of 1 RM in the bench press.