The effect of caffeinated coffee consumed at different doses on maximal strength

This study examined the acute effects of coffee providing 2 or 4 mg/kg caffeine on bench press and Smith machine squat one-repetition maximum (1RM) performance. Fifteen healthy, recreationally resistance-trained men aged 18–35 years, each with at least one year of resistance-training experience, completed a randomized, single-blind, placebo-controlled crossover study. Participants consumed instant coffee providing 2 or 4 mg/kg caffeine or decaffeinated coffee as placebo. The strength tests were performed 60 min after ingestion, with a 48–72 h washout between sessions. Data were analyzed using repeated-measures ANOVA and LSD post hoc tests. Caffeine condition had significant effects on bench press 1RM (F(2, 28) = 6.962, p = 0.004) and Smith machine squat 1RM (F(2, 28) = 5.539, p = 0.009). The 4 mg/kg condition produced significantly higher bench press and squat performance than placebo (p = 0.003 and p = 0.022, respectively) and the 2 mg/kg condition (p = 0.009 and p = 0.014, respectively). No significant differences were detected between the 2 mg/kg and placebo conditions for bench press (p = 0.396) or squat (p = 0.869). These findings apply to the acute conditions and 1RM tests examined in this sample and do not establish a general caffeine dose–response relationship.