2.3. Resistance Exercise Study Design
One week before starting the experimental session, maximal strength was assessed by one Repetition Maximum (1RM) test in bench press, leg press, seated cable row, and shoulder press. Participants were asked to abstain from performing the exercise 3 days before the 1RM test and experimental sessions, and to avoid consumption of caffeine for 24 h before testing.Then, in a randomized, double-blind, placebo-controlled, and cross-over design, participants consumed 6 mg per kg bodyweight caffeine or a placebo one hour before RE. After one hour, blood samples were taken from antecubital vein of the subjects; then, they participated in 3 sets of RE to failure with 85% of 1RM, consisting of bench press, leg press, seated cable row, and shoulder press. Two minutes of rest period between sets and exercise was taken. Additional blood samples were taken from the venous vein immediately after (Post) and 15 min after RE (15 min Post). After 3 days of washout, the subjects were recalled and treated with caffeine or placebo, with a change in supplementation and placebo, under the same conditions. Then, they participated in RE under the previous conditions again.