Purpose Considering the different function and ambiguity on the effectiveness of mixed creatine and caffeine supplementa- tion (CrH_Caf), this research was done to examine the combined effect of creatine supplement with hydrochloride chemical composition (CrH) plus caffeine supplement (Caf) on the repetition sustainability, resistance exercise volume plus testosterone (TST), and cortisol (COR) serum levels in young trained men. Methods Twelve eligible individuals were chosen conveniently as the sample. The research was done as double-blind under common and cross conditions in five circumstances: baseline, mixed (CrH: 0.03 g.kg−1 , Caf: 6 mg.kg−1 ), CrH (0.03 gr.kg−1 ), Caf (6 mg.kg −1 ), and placebo (PL). The resistance exercise included five sets of chest press and five sets of leg press with 60% of 1 RM intensity until failure. 5 ml of blood was taken at the end of each session from the brachial vein to evaluate hormonal levels. Results TST and COR serum concentration after CrH_Caf did not differ significantly with other conditions. The resistance exercise volume until failure was increased in the upper and lower body ( p ≤ 0.05) at CrH_Caf conditions compared to baseline and PL. Meanwhile, no significant difference was found between the conditions when comparing repetition sustain- ability until failure. Conclusion Overall, CrH_Caf mixed supplementation does not seem to have a synergistic effect on resistance performance and hormonal changes. Thus, CrH and Caf consumption separately can have a favorable impact for athletes.

Keywords