Dose response effects of a caffeine-containing energy drink on muscle performance: a repeated measures design

In a randomized order, twelve active participants ingested 1 and 3？mg of caffeine per kg of body weight using a commercially available energy drink (Fure？, ProEnergetics) or the same drink without caffeine (placebo; 0？mg/kg). After sixty minutes, resting metabolic rate, heart rate and blood pressure were determined. Then, half-squat and bench-press power production with loads from 10 to 100% of 1 repetition maximum was determined using a rotator encoder.In comparison to the placebo, the ingestion of the caffeinated drink increased mean arterial pressure (82？±？7？<？88？±？8？≈？90？±？6？mmHg for 0？mg/kg, 1？mg/kg, 3？mg/kg of caffeine, respectively; P？<？0.05) and heart rate (57？±？7？<？59？±？8？<？62？±？8 beats/min, respectively; P？<？0.05) at rest in a dose response manner, though it did not affect resting metabolic rate. While the ingestion of 1？mg/kg of caffeine did not affect maximal power during the power-load tests with respect to the placebo, 3？mg/kg increased maximal power in the half-squat (2554？±？167？≈？2549？±？161？<？2726？±？167？W, respectively; P？<？0.05) and bench-press actions (349？±？34？≈？358？±？35？<？375？±？33？W, respectively; P？<？0.05).A caffeine dose of at least 3？mg/kg in the form of an energy drink is necessary to significantly improve half-squat and bench-press maximal muscle power.