Tallis, Jason, Morris, Rhys, Bolt, Lee and Eustace, Steven (2025) Between session reliability of traditional and temporal bilateral and unilateral dynamic strength index calculations and association with sprint and change of direction performance. Journal of Strength and Conditioning Research. ISSN 1064-8011 (In Press)

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Abstract

The present study aimed to; 1) evaluate the between session reliability of traditional and temporal based bilateral and unilateral dynamic strength index (DSI); 2) determine the association between DSI and sprint and change of direction performance in participants clustered by DSI root metrics. Thirty-eight recreationally active males (age: 23.4 ± 3.4 years) completed 20-m sprints, 5-0-5 change of direction test, bilateral and unilateral countermovement jumps (CMJ), and isometric mid-thigh pulls (IMTP) on two occasions. Vertical ground reaction force profiles were assessed to determine traditional DSI (DSIT), DSI based on mean force achieved after 100ms (DSI100), 150ms (DSI150), the entire CMJ propulsive phase (DSIP), and CMJ propulsive impulse (DSII). Bayesian interclass correlation coefficients and multiple linear regression following K-means clustering were used to analyze the data. Between session reliability of DSI was poor-moderate (ICC = 0.24-0.76) and highest for DSIT measures, albeit with some uncertainty (95% HDI: 0.53-0.87). Bilateral temporal based DSI reliability was greater compared to unliteral equivalents, and temporal based DSI calculated for the non-dominant limb, and those determined over a small-time epoch for the dominant limb were poor. There was limited association across DSI measures and straight-line 20m sprint and 5-0-5 change of direction performance test. DSI100 for the dominant side had the strongest association with the performance outcomes (R2 = 0.33-0.36) and was improved in participants that expressed higher CMJ peak propulsive force. DSI should be used with caution with respect to exercise prescription for the intention of improving tasks requiring rapid horizontal center of mass translation.

Item Type:	Article
Keywords:	Strength Profiling, Resistance Training, Isometric Midthigh Pull, Vertical Jump, 48 Force Platform
Subjects:	Medicine and health > Physiology
Depositing User:	Steven Eustace
Date Deposited:	29 Aug 2025 08:22
Last Modified:	29 Aug 2025 10:00
URI:	https://repository.uwl.ac.uk/id/eprint/14025

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