Inter-Day Reliability of Countermovement Jump Metrics in Elite Academy Soccer Players

Lonergan, B; Cohen, DD; Williams, S; Lawson, R; Howarth, DJ; Johnson, DM

Inter-Day Reliability of Countermovement Jump Metrics in Elite Academy Soccer Players

Lonergan, B Cohen, DD Williams, S Lawson, R Howarth, DJ Johnson, DM

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Publisher:: International Universities Strength and Conditioning Association
Publication Type:: Journal Article
Citation:: International Journal of Strength and Conditioning, 5, (1)

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Field	Value	Language
dc.contributor.author	Lonergan, B
dc.contributor.author	Cohen, DD
dc.contributor.author	Williams, S
dc.contributor.author	Lawson, R
dc.contributor.author	Howarth, DJ
dc.contributor.author	Johnson, DM
dc.date.accessioned	2026-05-20T05:38:04Z
dc.date.available	2026-05-20T05:38:04Z
dc.identifier.citation	International Journal of Strength and Conditioning, 5, (1)
dc.identifier.issn	2634-2235
dc.identifier.issn	2634-2235
dc.identifier.uri	http://hdl.handle.net/10453/195096
dc.description.abstract	The purpose of this study was to determine the inter-day reliability of countermovement jump (CMJ) force plate metrics in elite male academy soccer players. Fourteen players performed 3 CMJ s on 3 separate days over an 8-day period during a typical in-season competition and training period. Absolute (coefficient of variation (CV)) and relative reliability (interclass coefficient (ICC)) were calculated using two inter-day combinations condition 1 Monday-Tuesday, condition 2 Monday-Monday and using two data treatment methods mean of trials ( mean3 ) and single trial with the highest Flight Time Contraction Time ( BestFT CT ). In the mean3, Monday-Tuesday condition, all CV s except for peak landing force were 10 , with most 5 , while all ICC s were 0.75 (good), and most ICC s 0.9 (excellent). Several metrics had lower CV s and higher ICC s in condition 1 than condition 2 and in mean3 than BestFT CT. Importantly, in the context of using downward eccentric phase metrics in monitoring, eccentric deceleration rate of force development, durations, power and displacement within this phase demonstrated good-excellent absolute reliability (CVs between 2.9 and 7.03 ). Overall, CV s were substantially lower than most previous studies, but similar to investigations involving elite team sport athletes who also perform the CMJ regularly. Our findings suggest that metric reliability is enhanced by this exposure and by a competitive environment, and that reliability data obtained in populations without these characteristics is not generalizable to the elite setting. Practitioners should endeavor to assess inter-day reliability within their team. In-season implementation represents an ecologically valid option.
dc.language	en
dc.publisher	International Universities Strength and Conditioning Association
dc.relation.ispartof	International Journal of Strength and Conditioning
dc.relation.isbasedon	10.47206/ijsc.v5i1.504
dc.rights	info:eu-repo/semantics/openAccess
dc.title	Inter-Day Reliability of Countermovement Jump Metrics in Elite Academy Soccer Players
dc.type	Journal Article
utslib.citation.volume	5
pubs.organisational-group	University of Technology Sydney
pubs.organisational-group	University of Technology Sydney/Faculty of Health
utslib.copyright.status	open_access	*
pubs.consider-herdc	true
dc.rights.license	This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0). To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/
dc.date.updated	2026-05-20T05:38:03Z
pubs.issue	1
pubs.publication-status	Published
pubs.volume	5
utslib.citation.issue	1

Abstract:

The purpose of this study was to determine the inter-day reliability of countermovement jump (CMJ) force plate metrics in elite male academy soccer players. Fourteen players performed 3 CMJ s on 3 separate days over an 8-day period during a typical in-season competition and training period. Absolute (coefficient of variation (CV)) and relative reliability (interclass coefficient (ICC)) were calculated using two inter-day combinations condition 1 Monday-Tuesday, condition 2 Monday-Monday and using two data treatment methods mean of trials ( mean3 ) and single trial with the highest Flight Time Contraction Time ( BestFT CT ). In the mean3, Monday-Tuesday condition, all CV s except for peak landing force were 10 , with most 5 , while all ICC s were 0.75 (good), and most ICC s 0.9 (excellent). Several metrics had lower CV s and higher ICC s in condition 1 than condition 2 and in mean3 than BestFT CT. Importantly, in the context of using downward eccentric phase metrics in monitoring, eccentric deceleration rate of force development, durations, power and displacement within this phase demonstrated good-excellent absolute reliability (CVs between 2.9 and 7.03 ). Overall, CV s were substantially lower than most previous studies, but similar to investigations involving elite team sport athletes who also perform the CMJ regularly. Our findings suggest that metric reliability is enhanced by this exposure and by a competitive environment, and that reliability data obtained in populations without these characteristics is not generalizable to the elite setting. Practitioners should endeavor to assess inter-day reliability within their team. In-season implementation represents an ecologically valid option.

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http://hdl.handle.net/10453/195096