The acute effects of caffeine intake on time under tension and power generated during the bench press movement

Abstract

Background: The 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 (VE MEAN ) of the bench press movement. Methods: The 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 (G CAF ), while the control group was given a placebo (G CON ). 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. Results: The repeated measures ANOVA between the G CAF and G CON 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 G CAF ) to the one ingesting a placebo (15.332 s G CON ) at p = 0.002. Significant differences were also observed in mean velocity during the eccentric phase of movement (0.690 m/s in the G CAF to 0.609 in G CON with p = 0.002). There were no significant differences in generated power and velocity in the CON phase of the movement between the G CAF and G CON. Conclusions: The 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.

The effects of different doses of caffeine on maximal strength and strength-endurance in women habituated to caffeine

“…Only one previous study analyzed the impact of CAF intake on TUT by using a cross-sectional experiment with a group that ingested 5 mg/kg/b.m. of CAF or PLAC before performing the strength-endurance bench press exercise at 70% 1RM performed to muscular failure [7]. This investigation showed a signi cant decrease in TUT in the group that received CAF compared to the control group, what is contradictory to the results of our study.…”

“…This investigation showed a signi cant decrease in TUT in the group that received CAF compared to the control group, what is contradictory to the results of our study. Con icting results between presented studies and Wilk et al [7] can be related to the gender difference of the subjects (male vs female). Sex may have a signi cant effect on skeletal muscle morphology and function [35], muscle substrate utilization and neuromuscular activation [53].…”

“…Yet, this explanation remains speculative until further investigation con rms a higher effect of CAF in women vs men in the local strength-endurance test because current evidence suggests an effect of similar magnitude in cycling endurance activities [16,17], and a tendency for a lower effect of CAF on strength-endurance performance in women has also been found [33]. However, for assessing local strength-endurance and to test the effectiveness of dietary supplements during resistance exercise, the use of crossover designs and the evaluation of not only the number of REP, but also TUT may be recommended [7].…”

“…The ergogenic effect of CAF has been found when consumed at doses ranging from 3 to 13 mg/kg body mass (b.m.) and ingested in the form of capsules 30 to 90 minutes before exercise [6,7], although the use of high doses of CAF normally increases the prevalence of caffeine-associated sideeffects [8]. Interestingly, the manner of CAF administration seems to be less relevant than the dosage and timing, as ergogenic effects of caffeine on resistance-based exercise has been found after consuming caffeinated energy drinks [9] and gels [10], and coffee [11].…”

Placebo effect of caffeine on maximal strength and strength-endurance in healthy recreationally trained women habituated to caffeine

“…Furthermore, urinary caffeine concentration has increased since the removal of caffeine from the list of banned substances of the World Antidoping Agency in 2004 suggesting an increasing use of this stimulant in elite sport [2]. In the last years, there has been a burst of research that supports the performance-enhancing effects of caffeine across a wide range of sporting activities including aerobic exercise [3] anaerobic-like exercise [4], and resistance exercise [5][6][7]. Overall, there is ample consensus to consider the antagonistic role of caffeine and its two metabolites, paraxanthine and theophylline, in adenosine receptors as the main mechanism behind its ergogenic effects during exercise, as caffeine can bind adenosine A 1 , A 2A and A 2B receptors in the central nervous system, reducing the fatiguing effect of adenosine [8].…”