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Comparative effect size distributions in strength and conditioning and implications for future research: a meta-analysis.

Swinton, Paul Alan; Murphy, Andrew

Authors



Abstract

Controlled experimental designs are frequently used in strength and conditioning (S&C) to determine which interventions are most effective. The purpose of this large meta-analysis was to quantify the distribution of comparative effect sizes in S&C to determine likely magnitudes and inform future research regarding sample sizes and inference methods. Baseline and follow-up data were extracted from a large database of studies comparing at least two active S&C interventions. Pairwise comparative standardised mean difference effect sizes were calculated and categorised according to the outcome domain measured. Hierarchical Bayesian meta-analyses and meta-regressions were used to model overall comparative effect size distributions and correlations, respectively. The direction of comparative effect sizes within a study were assigned arbitrarily (e.g. A vs. B, or B vs. A), with bootstrapping performed to ensure effect size distributions were symmetric and centred on zero. The middle 25, 50, and 75% of distributions were used to define small, medium, and large thresholds, respectively. A total of 3874 pairwise effect sizes were obtained from 417 studies comprising 958 active interventions. Threshold values were estimated as: small = 0.14 [95%CrI: 0.12 to 0.15]; medium: = 0.29 [95%CrI: 0.28 to 0.30]; and large = 0.51 [95%CrI: 0.50 to 0.53]. No differences were identified in the threshold values across different outcome domains. Correlations ranged widely (0.06 ≤ r ≤0.36), but were larger when outcomes within the same outcome domain were considered. The finding that comparative effect sizes in S&C are typically below 0.30 and can be moderately correlated has important implications for future research. Sample sizes should be substantively increased to appropriately power controlled trials with pre-post intervention data. Alpha adjustment approaches used to control for multiple testing should account for correlations between outcomes and not assume independence.

Citation

SWINTON, P.A. and MURPHY, A. [2024]. Comparative effect size distributions in strength and conditioning and implications for future research: a meta-analysis. International journal of strength and conditioning [online], (accepted). To be made available from: https://journal.iusca.org/index.php/Journal/issue/view/9

Journal Article Type Article
Acceptance Date Jan 19, 2024
Deposit Date Jan 25, 2024
Publicly Available Date Jan 25, 2024
Journal International journal of strength and conditioning
Print ISSN 2634-2235
Electronic ISSN 2634-2235
Publisher International Universities Strength and Conditioning Association (IUSCA)
Peer Reviewed Peer Reviewed
Keywords S&C; Evaluation; Effect size; Statistical power; Sample size
Public URL https://rgu-repository.worktribe.com/output/2218514
Related Public URLs https://rgu-repository.worktribe.com/output/1764885 (Pre-print published on SportRixiv)

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SWINTON 2024 Comparative effect size (AAM) (489 Kb)
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Publisher Licence URL
https://creativecommons.org/licenses/by/4.0/

Copyright Statement
Copyright: © 2024 by the authors. Licensee IUSCA, London, UK. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/ 4.0/).





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