TY - JOUR

T1 - Caffeine and bicarbonate for speed. A meta-analysis of legal supplements potential for improving intense endurance exercise performance

AU - Christensen, Peter Møller

AU - Shirai, Yusuke

AU - Ritz, Christian

AU - Nordsborg, Nikolai Baastrup

N1 - CURIS 2017 NEXS 146

PY - 2017

Y1 - 2017

N2 - A 1% change in average speed is enough to affect medal rankings in intense Olympic endurance events lasting ~45 s to 8 min which for example includes 100 m swimming and 400 m running (~1 min), 1,500 m running and 4000 m track cycling (~4 min) and 2,000 m rowing (~6-8 min). To maximize the likelihood of winning, athletes utilizes legal supplements with or without scientifically documented beneficial effects on performance. Therefore, a continued systematic evidence based evaluation of the possible ergogenic effects is of high importance. A meta-analysis was conducted with a strict focus on closed-end performance tests in humans in the time domain from 45 s to 8 min. These test include time-trials or total work done in a given time. This selection criterion results in a high relevance for athletic performance. Only peer-reviewed placebo controlled studies were included. The often applied and potentially ergogenic supplements beta-alanine, bicarbonate, caffeine and nitrate were selected for analysis. Following a systematic search in Pubmed and SportsDiscuss combined with evaluation of cross references a total of 7 (beta-alanine), 25 (bicarbonate), 9 (caffeine), and 5 (nitrate) studies was included in the meta-analysis. For each study, performance was converted to an average speed (km/h) from which an effect size (ES; Cohens d with 95% confidence intervals) was calculated. A small effect and significant performance improvement relative to placebo was observed for caffeine (ES: 0.41 [0.15-0.68], P = 0.002) and bicarbonate (ES: 0.40 [0.27-0.54], P < 0.001). Trivial and non-significant effects on performance was observed for nitrate (ES: 0.19 [-0.03-0.40], P = 0.09) and beta-alanine (ES: 0.17 [-0.12-0.46], P = 0.24). Thus, caffeine's and bicarbonate's ergogenic effect is clearly documented for intense endurance performance. Importantly, for all supplements an individualized approach may improve the ergogenic effect on performance.

AB - A 1% change in average speed is enough to affect medal rankings in intense Olympic endurance events lasting ~45 s to 8 min which for example includes 100 m swimming and 400 m running (~1 min), 1,500 m running and 4000 m track cycling (~4 min) and 2,000 m rowing (~6-8 min). To maximize the likelihood of winning, athletes utilizes legal supplements with or without scientifically documented beneficial effects on performance. Therefore, a continued systematic evidence based evaluation of the possible ergogenic effects is of high importance. A meta-analysis was conducted with a strict focus on closed-end performance tests in humans in the time domain from 45 s to 8 min. These test include time-trials or total work done in a given time. This selection criterion results in a high relevance for athletic performance. Only peer-reviewed placebo controlled studies were included. The often applied and potentially ergogenic supplements beta-alanine, bicarbonate, caffeine and nitrate were selected for analysis. Following a systematic search in Pubmed and SportsDiscuss combined with evaluation of cross references a total of 7 (beta-alanine), 25 (bicarbonate), 9 (caffeine), and 5 (nitrate) studies was included in the meta-analysis. For each study, performance was converted to an average speed (km/h) from which an effect size (ES; Cohens d with 95% confidence intervals) was calculated. A small effect and significant performance improvement relative to placebo was observed for caffeine (ES: 0.41 [0.15-0.68], P = 0.002) and bicarbonate (ES: 0.40 [0.27-0.54], P < 0.001). Trivial and non-significant effects on performance was observed for nitrate (ES: 0.19 [-0.03-0.40], P = 0.09) and beta-alanine (ES: 0.17 [-0.12-0.46], P = 0.24). Thus, caffeine's and bicarbonate's ergogenic effect is clearly documented for intense endurance performance. Importantly, for all supplements an individualized approach may improve the ergogenic effect on performance.

KW - Performance

KW - Supplements

KW - Ergogenic aids

KW - Intense exercise

KW - Running

KW - Cycling

KW - Rowing

KW - Swimming

U2 - 10.3389/fphys.2017.00240

DO - 10.3389/fphys.2017.00240

M3 - Review

C2 - 28536531

VL - 8

JO - Frontiers in Physiology

JF - Frontiers in Physiology

SN - 1664-042X

M1 - 240

ER -