Force vs. impulse: assessing the applicability of dynamic strength 
indices in individualized training recommendations

Yuhang Liu; Chris Bishop; Lachlan James; Changda Lu; Fanhao Meng; Xiaoyi Yuan

doi:10.5114/biolsport.2026.157994

eISSN: 2083-1862
ISSN: 0860-021X

Biology of Sport

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abstract:

Original paper

Force vs. impulse: assessing the applicability of dynamic strength indices in individualized training recommendations

Yuhang Liu

¹

,

Chris Bishop

²

,

Lachlan P. James

³

,

Changda Lu

⁴

,

Fanhao Meng

⁵

,

Xiaoyi Yuan

^{1, 6}

School of Education, Beijing Sport University, Beijing, China
London Sports Institute, Middlesex University, London, United Kingdom
Sport, Performance, and Nutrition Research Group, School of Allied Health, Human Services, & Sport, La Trobe University, Melbourne, VIC, Australia
School of Sport Science, Beijing Sport University, Beijing, China
School of Strength and Conditioning, Beijing Sport University, Beijing, China
The Key Laboratory of Sports Training, General Administration of Sport of China, Beijing, China

Biol Sport. 2026;43:743–752

DOI: https://doi.org/10.5114/biolsport.2026.157994

Online publish date: 2026/01/02

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In this cross-sectional investigation, we aimed to compare impulse-derived (iDSI) and forcederived (fDSI) dynamic strength indices to determine their consistency in guiding individualized training recommendations. It also assessed the agreement between training prescriptions based on these indices and analyzed individualized neuromuscular profiles through case study comparisons. Twenty male skeleton and bobsled athletes performed countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) assessments in a counterbalanced order. Wilcoxon signed-rank tests were conducted to examine differences between fDSI and iDSI. Spearman correlation coefficients quantified intra-group relationships, and linear regression analysis evaluated the model fit between indices. Cohen’s kappa (κ) was applied to assess agreement in training classifications derived from fDSI and iDSI. Both indices showed limitations in representing lower-limb neuromuscular function (Z = –3.72, p < 0.01, large effect). A moderate correlation was observed between iDSI and fDSI (rs = 0.47, p < 0.05), with moderate agreement in their training recommendations (κ = 0.52, 95% CI: [0.38, 0.66]). Case-study analyses revealed substantial inter-athlete variability in CMJ force–time characteristics, highlighting the need for individualized interpretation within performance profiling. Incorporating phase-specific, multi-metric evaluations of force–time variables may improve the precision of training decisions and better inform athletespecific programming.

keywords:

Force vs. impulse: assessing the applicability of dynamic strength indices in individualized training recommendations

Yuhang Liu 1 , Chris Bishop 2 , Lachlan P. James 3 , Changda Lu 4 , Fanhao Meng 5 , Xiaoyi Yuan 1, 6

Countermovement jump, Force platform, Resistance training, Strength diagnosis, Strength testing

Yuhang Liu

¹

,

Chris Bishop

²

,

Lachlan P. James

³

,

Changda Lu

⁴

,

Fanhao Meng

⁵

,

Xiaoyi Yuan

^{1, 6}