Plain language summary
Caffeine has been shown to have a positive effect on resistance performance but few studies have specifically examined the effects of caffeine on power outcomes. Modern athletic training programmes have shifted focus from concentric strength training to eccentric resistance training, and the flywheel paradigm has been found to be an effective strategy to improve athletic performance and prevent injury. The aim of this randomised, double-blind study was to assess the effects of caffeine on in lower body power outcomes in resistance exercise utilising a flywheel device. Twenty healthy, active men were randomised to receive either a caffeine or placebo supplement 45 minutes before completing eight repetitions of flywheel half-squat exercise at four differential loads to assess both mean power and peak power values. Participants attended test sessions four times over two consecutive weeks with at least 72 hours between sessions. This study found that compared with placebo, caffeine supplementation improved power outcomes significantly in both mean and peak power outcomes with respect to both concentric and eccentric movement phases. Based on these results, the authors conclude that the application of 6 mg/kg of caffeine may be considered to maximise physical performance in sports involving high demands of resistance.
undefined: Despite the demonstrated evidence of the importance of eccentric contractions in sports performance, no research has evaluated the ergogenic effects of caffeine on this type of contraction means during flywheel exercises. Therefore, the aims of the present study were to compare the power outcomes, using different inertial loads, between caffeine and placebo conditions. Twenty-four young, healthy, and active men (age: 22.5 ± 4.8 years) took part in the study. A crossed, randomised double-blind design was used to analyse the effects of caffeine on lower limb power outcomes during a flywheel half-squat exercise. Participants completed four sets of eight all-out repetitions with a fixed three-minutes rest interval, and each set was performed using different inertial loads (i.e., 0.025, 0.050, 0.075 and 0.100 kg·m ). Both the mean power (MP) and peak power (PP) in concentric (CON) and eccentric (ECC) movement phases at each inertial load were recorded after participants were administered either a caffeine supplement (6 mg·kg ) or placebo (sucrose). Participants receiving a caffeine supplementation demonstrated improvements versus the placebo in total MP (MP ), as well as MP in CON phase (MP ) and in ECC phase (MP ) at each inertial load (22.68 to 26.53%; < 0.01, effect size (ES) = 0.89⁻1.40). In addition, greater improvements with caffeine ingestion were obtained with respect to the placebo condition (18.79 to 24.98%; < 0.01, ES = 1.03⁻1.40) in total PP (PP ), as well as PP in CON phase (PP ) and in ECC phase (PP ) at each inertial load. Thus, the supplementation of 6 mg·kg caffeine may be considered to maximise on-field physical performance in those sports characterised by high demands of resistance.