Caffeine Increases Endurance Performance via Changes in Neural and Muscular Determinants of Performance Fatigability

Abstract

Purpose: In the present study, we tested the hypothesis that caffeine would increase endurance performance via attenuation of neural and muscular determinants of performance fatigability during high-intensity, whole-body exercise. Methods: Ten healthy males cycled until exhaustion (89% ± 2% of VO 2max ) after the ingestion of caffeine or placebo. During another four visits, the same exercise was performed after either caffeine or placebo ingestion but with exercise discontinued after completing either 50% or 75% of the duration of placebo trial. An additional trial with caffeine ingestion was also performed with interruption at the placebo time to exhaustion (isotime). Performance fatigability was measured via changes in maximal voluntary contraction, whereas neural and muscular determinants of performance fatigability were quantified via preexercise to postexercise decrease in quadriceps voluntary activation (VA) and potentiated twitch force, respectively. Results: Compared with the placebo, caffeine increased time to exhaustion (+14.4 ± 1.6%, P = 0.017, 314.4 ± 47.9 vs 354.9 ± 40.8 s). Caffeine did not change the rate of decline in maximal voluntary contraction (P = 0.209), but caffeine reduced the twitch force decline at isotime when stimulating at single twitch (−58.6 ± 22.4 vs À45.7 ± 21.9%, P = 0.014) and paired 10 Hz electrical stimuli (−37.3 ± 13.2 vs À28.2 ± 12.9%, P = 0.025), and reduced the amplitude of electromyography signal during cycling at isotime (P = 0.034). The decline in VA throughout the trial was lower (P = 0.004) with caffeine (−0.5 ± 4.2%) than with placebo (−5.8 ± 8.5%). Caffeine also maintained peripheral oxygen saturation at higher levels (95.0 ± 1.9%) than placebo (92.0 ± 6.2%, P = 0.016). Conclusions: Caffeine ingestion improves performance during high-intensity, whole-body exercise via attenuation of exercise-induced reduction in VA and contractile function.

Overview of Caffeine Effects on Human Health and Emerging Delivery Strategies

“…El Far et al studied the effect of caffeine and other natural substances on the senescent cells of colon and breast cancers. After inducing senescence with doxorubicin, the cells were treated with various doses of caffeine (0, 5,10,15,20,30,40,50, and 60 mM). The IC 50 of caffeine against doxorubicin-treated HCT116 and MCF7 cells was 13.36 ± 2.29 mM and 17.67 ± 3.98 mM, respectively.…”

“…Indeed, their ingestion is widely believed to have fewer or no adverse effects on humans than most synthetic molecules, and they are also cheaper and easier to obtain [ 2 , 3 , 4 ]. Caffeine, in particular, has been the subject of intense and in-depth research on the human organism regarding its health-promoting effects and possible beneficial effects on the performance of athletes, especially through its ability to improve anaerobic and aerobic performance, muscle efficiency, and speed, and to reduce fatigue [ 5 , 6 , 7 , 8 , 9 ]. Caffeine is probably the most commonly ingested psychoactive substance in the world, found mainly in coffee, soft drinks, tea, cocoa and chocolate-like products, yerba matte leaves, guarana berries, and some pharmaceuticals [ 10 ].…”

Caffeine Improves Sprint Time in Simulated Freestyle Swimming Competition but Not the Vertical Jump in Female Swimmers

“…CAF's binding to these receptors might boost alertness and reduce feelings of fatigue, which may lead to an enhanced exercise performance [8]. In addition, CAF may increase motor neuron activation and prevent the decrease in voluntary activation caused by exercise-induced exhaustion; these effects may potentially contribute to performance [9,10]. Additionally, CAF enhances the Na + -K + pump activation and an enhanced high-intensity sprint performance was reported with increased blood epinephrine and norepinephrine concentration [11].…”

Effects of Caffeine Intake on Endurance Running Performance and Time to Exhaustion: A Systematic Review and Meta-Analysis

“…Caffeine (1,3,7-trimethylxanthine) is one of the most widely consumed performance-enhancing substances in sport due to its well-established ergogenic effects in a myriad of exercise situations [ 1 , 2 , 3 ]. Caffeine’s ergogenicity is obtained in humans through several physiological mechanisms including increased central nervous system drive, increased catecholamine release, and enhanced skeletal muscle contractile capacity [ 4 , 5 , 6 ]. The benefits of caffeine in sport can also be obtained by psychobiological responses, mainly displayed as an increase in physical performance when the individual believes that they have received an ergogenic dose of caffeine, a phenomenon known as the placebo effect of caffeine [ 7 , 8 ].…”