Caffeine Supplementation Effects on Concurrent Training Performance in Resistance-Trained Men: A Double-Blind Placebo-Controlled Crossover Study.

Purpose: The aim of the present study was to investigate the effects of acute caffeine supplementation on the performance during a session of resistance training alone (RT) or in combination with aerobic training (i.e. concurrent training; CT). Method: Fourteen resistance-trained men (23.1 ± 4.2 years) were recruited and performed both RT and CT under three different conditions: control (CONT), placebo (PLA), and caffeine (CAF; 6 mg.kg-1 ) for a total of six experimental conditions. Results: Both total and per set number of repetitions, and total volume load were lower during CT as compared to RT, irrespective of the supplementation condition (all p  < .001), whereas a supplementation main effect was observed for the total number of repetitions ( p  = .001), the number of repetitions in the first ( p  = .002) and second sets ( p  = .001), and total volume load ( p  = .001). RPE values were higher after the CT sessions than after the RT sessions ( p  < .001), whereas no differences were observed between supplementation conditions ( p  = .865). Conclusions: Caffeine supplementation was not sufficient to minimize the acute interference effect on strength performance in a CT session when compared to RT alone. In contrast, caffeine improved strength performance during the first set of both CT and RT, while maintaining a similar RPE between the supplementation conditions. However, the overall effect was small.