Effects of caffeinated coffee on physical and cognitive performance: Chronotype and time of day study.

This study examined the effects of caffeinated coffee (3 mg/kg) compared to decaffeinated coffee (placebo) on physical and cognitive performance in trained male athletes with morning (MT) and evening (ET) chronotypes, all of whom had moderate caffeine intake. Seventeen trained male athletes participated in various tests, including CP (a flanker task), hand grip strength test, back strength test, lower body Wingate sprint tests (peak and average power), and rating of perceived exertion (using the Borg Scale). The tests were conducted at two times of day: mornings (08:00 h-10:00 h) and evenings (16:00 h-18:00 h). Results indicated that caffeinated coffee significantly enhanced handgrip strength [F(1, 15) = 11.200, p = 0.001, η²p = .427], back strength [F(1, 15) = 8.695, p = 0.001, η²p = 0.367], and lower body Wingate test performance, including peak strength [F(1, 15) = 8.384, p = 0.001, η²p = 0.359] and mean strength [F(1, 15) = 8.304, p = 0.001, η²p = 0.356], regardless of chronotype. Conversely, no significant differences were observed in the cognitive performance (CP) measured by the flanker task and in Borg's perceived exertion ratings. When analyzing the interaction between groups × CAF & PLA, significant differences were found in the handgrip strength test [F(3, 45) = 17.443, p = 0.001, η²p = 0.538], back strength test [F(3, 45) = 19.926, p = 0.001, η²p = 0.571], peak power [F(3, 45) = 12.285, p = 0.001, η²p = 0.450], and average power [F(3, 45) = 6.633, p = 0.009, η²p = 0.307]. However, no significant differences were noted in cognitive performance (CP) and Borg perceived exertion ratings. These findings suggest that chronotype, timing of training, and caffeine consumption can significantly influence physical performance in trained men with moderate caffeine intake.