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Vol.:(0123456789)
Sports Medicine (2020) 50:717–729
https://doi.org/10.1007/s40279-019-01211-9
SYSTEMATIC REVIEW
Acute Eects ofCaeine Supplementation onMovement Velocity
inResistance Exercise: ASystematic Review andMeta‑analysis
JavierRaya‑González1· TaraRendo‑Urteaga1· RaúlDomínguez1· DanielCastillo1·
AlejandroRodríguez‑Fernández1· JozoGrgic2
Published online: 23 October 2019
© Springer Nature Switzerland AG 2019
Abstract
Background Several studies investigated the effects of caffeine supplementation on movement velocity in resistance exercise.
However, these studies presented inconsistent findings.
Objective This paper aimed to: (a) review the studies that explored the effects of caffeine supplementation on movement
velocity in resistance exercise; and (b) pool their results using a meta-analysis.
Methods A search for studies was performed through seven databases. Random-effects meta-analyses of standardized mean
differences (SMD) were performed to analyze the data. Sub-group meta-analyses explored the effects of caffeine on differ-
ent velocity variables (i.e., mean andpeak velocity), different loads (i.e., low, moderate, and high loads), and upper- and
lower-body exercises.
Results Twelve studies met the inclusion criteria. In the main meta-analysis, in which we pooled all available studies,
the SMD favored the caffeine condition (SMD = 0.62; 95% confidence interval [CI]: 0.39–0.84; p < 0.001). Sub-group
analyses indicated that caffeine significantly enhances mean (SMD = 0.80; 95% CI: 0.48–1.12; p < 0.001) and peak veloc-
ity (SMD = 0.41; 95% CI: 0.08–0.75; p = 0.014), movement velocity with low loads (SMD = 0.78; 95% CI: 0.41–1.14;
p < 0.001), moderate loads (SMD = 0.58; 95% CI: 0.25–0.91; p = 0.001), and high loads (SMD = 0.70; 95% CI: 0.33–1.07;
p < 0.001), as well as in lower-body (SMD = 0.82; 95% CI: 0.42–1.23; p < 0.001) and upper-body exercises (SMD = 0.59;
95% CI: 0.37–0.82; p < 0.001).
Conclusion Acute caffeine supplementation is highly ergogenic for movement velocity in resistance exercise. Sub-group
analyses indicated that caffeine ingestion is ergogenic: (a) for both mean and peak velocity; (b) for movement velocity when
exercising with low, moderate and high loads, and (c) for movement velocity in both lower- and upper-body exercises. Previ-
ous meta-analyses that explored the effects of caffeine on various aspects of resistance exercise performance (i.e., muscular
strength and endurance) reported trivial to moderate ergogenic effects (effect size range: 0.16–0.38). In the present meta-
analysis, the pooled effect size ranged from 0.41 to 0.82. From a resistance exercise performance standpoint, this suggests
that caffeine has the most pronounced performance-enhancing effects on movement velocity.
1 Introduction
The 2018 International Olympic Committee consensus
statement classified caffeine as a nutritional supplement
that has good evidence of benefits for enhancing exercise
performance [1]. As such, caffeine is widely consumed
by athletes [2]. Studies that examined the prevalence of
caffeine ingestion among different groups of athletes
reported that those competing in strength- and power-
based sports are among the highest users of caffeine—in
terms of the urine concentration of caffeine [2].
Many primary studies and several meta-analy-
ses have explored the effects of caffeine on muscle
strength [3–10]. The currently published meta-analyses
investigated the effects of caffeine on one-repetition
maximum (1RM), isokinetic, and isometric strength
[3–5]. These meta-analyses [3–5] reported ergogenic
effects of caffeine on strength in the effect size mag-
nitude of 0.16 for isokinetic strength (95% confidence
* Jozo Grgic
jozo.grgic@live.vu.edu.au
1 Faculty ofHealth Sciences, Universidad Isabel I, Burgos,
Spain
2 Institute forHealth andSport (IHES), Victoria University,
Melbourne, VIC, Australia
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