Caffeine Dose and Duration in Habitual Female Users

This study compares the effects of acute (single-session) and short-term (7-day) consumption of different doses of caffeine (3 and 6 mg/kg) on maximal strength, strength endurance, vertical jump, and medicine ball throw performance in habitual caffeine-consuming women (daily intake of 5 mg/kg). Thirty-six resistance-trained women were randomly assigned to three groups: 3 mg/kg caffeine, 6 mg/kg caffeine, or placebo in a double-blind crossover design. Participants completed both acute (60 min pre-exercise) and short-term (7 consecutive days) protocols. The main findings showed that acute ingestion of 6 mg/kg caffeine impaired peak power in the maximal strength test, while short-term consumption of the same dose improved peak power in the strength-endurance test. The 3 mg/kg dose was ineffective in all conditions. Caffeine did not affect jump or throw performance. The study highlights the need for individualized caffeine guidelines based on timing, dosage, and habituation status.

Inclusion Criteria: Absence of neuromuscular and musculoskeletal disorders At least 2 years of regular resistance training experience (minimum 3 sessions per week) At least 6 months of resistance training prior to enrollment Absence of renal and hepatic disorders Daily caffeine consumption of 5 mg/kg body weight (based on questionnaire) No use of specific medications or supplements that could affect study outcomes (e.g., beta-alanine, creatine, pre-workout supplements) - Exclusion Criteria: Occurrence of any injury during the study Failure to adhere to the supplement consumption protocol Withdrawal from the study-