Wickwire, J., Green, J. M., Gendel, S., McLester, J. R., Pritchett, R., & Kovacs, M. (2006). The effects of caffeine on reps to failure and RPE during resistance training. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 1766.

This study examined the effects of caffeine on resistance training (repetitions, rating of perceived exertion, heart rate). Recreationally trained males (N = 7) and females (N = 3) were tested for ~10 RM on bench press and leg press. In sessions 2 and 3, caffeine (~6mg/kg) or placebo was ingested one hour before arrival. Ss performed three sets to failure on bench and leg presses. The number of successful repetitions, peak heart rate, and Omni RPE were recorded for each set. Ss rested for three minutes between sets and five minutes between exercises.

During the third set for the leg press, repetitions and peak heart rate were significantly higher for the caffeine condition compared to the placebo. However, no significant difference was found between conditions for RPE during any set of the leg press. Similar RPE with higher repetitions and peak heart rate suggests caffeine may have blunted the pain response during set three, possibly delaying subjective fatigue. No significant differences were observed for repetitions, RPE, or peak heart rate for the bench press.

Implication. Caffeine may affect the latter sets of some exercises in resistance training. The effect may be selective.

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