Abstract
BackgroundThe ability to generate high levels of power is one of the key factors determining success in many sport disciplines. Although there are studies confirming ergogenic effects of caffeine (CAF) on different physical and mental abilities, much controversy remains about its influence on power. The main goal of this study was to assess the effects of caffeine supplementation on time under tension (TUT) and the number of performed repetitions (REP). The second objective was to determine the effects of CAF supplementation on power (P) and movement velocity (V) during the bench press movement. Additionally the authors evaluated whether CAF has a significant effect on velocity of the bar in the eccentric (ECC) phase (VEMEAN) of the bench press movement.MethodsThe study included 20 men (20–31 yrs., 87.3 ± 7.7 kg) with at least 2 years of experience in resistance training. The study participants were divided randomly into two groups: the supplemented group ingested caffeine before exercise (GCAF), while the control group was given a placebo (GCON). The exercise protocol consisted of performing the bench press movement with a load equal to 70%1RM with maximal possible velocity (X/0/X/0). The experimental sets were performed to momentary muscular failure.ResultsThe repeated measures ANOVA between the GCAF and GCON groups revealed statistically significant differences in 2 variables. Post-hoc tests demonstrated statistically significant differences in TUT when comparing the group supplemented with caffeine (13.689 s GCAF) to the one ingesting a placebo (15.332 s GCON) at p = 0.002. Significant differences were also observed in mean velocity during the eccentric phase of movement (0.690 m/s in the GCAF to 0.609 in GCON with p = 0.002). There were no significant differences in generated power and velocity in the CON phase of the movement between the GCAF and GCON.ConclusionsThe main finding of the study is that CAF ingestion increases movement velocity of the bar in the eccentric phase of the movement, what results in shortening of the time under tension (TUT) needed for performing a specific number of repetitions, without decreasing power and velocity in the CON phase of the movement.
Highlights
The ability to generate high levels of power is one of the key factors determining success in many sport disciplines
The ability to generate high levels of power has been indicated as a determinant of success in sports that require an optimal ratio of strength to velocity when performing a motor activity [1, 2]
One should stress that most studies that have analyzed the effect of CAF intake on exercise volume, both those that have demonstrated a significant effect on exercise capacity [33, 34, 37, 60, 63] and those which did not confirm such effects [14, 62], evaluated exercise volume using the number of REP or tonnage
Summary
The ability to generate high levels of power is one of the key factors determining success in many sport disciplines. The ability to generate high levels of power has been indicated as a determinant of success in sports that require an optimal ratio of strength to velocity when performing a motor activity [1, 2]. Studies have shown faster neuromuscular conduction [31], increased motor unit activation [32, 33], and increased number of repetitions (REP) in the bench press following caffeine intake 60 min before exercise, compared with a placebo [33, 34]. One should emphasize that previous research on CAF supplementation and the level of strength and power, as well as the number of performed repetitions considered resistance exercises performed at volitional or maximal velocity (V) of the entire movement, without a precise control of movement tempo during the concentric (CON) and eccentric (ECC) phases. Wilk et al [44] demonstrated significant differences in TUT and REP between the
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