Author Identifier (ORCID)
Paul Comfort: https://orcid.org/0000-0002-1131-8626
Abstract
Purpose: The aim of this study was to evaluate whether unilateral and bilateral assessments display comparable results during the isometric long-lever bridge and to examine the directionality of asymmetry fluctuations across testing occasions. Methods: Forty-four participants comprising of 30 men (age: 19.4 ± 1.3 years; height: 179.8 ± 6.3 cm; body mass: 80.4 ± 10.3 kg) and 14 women (age: 20.0 ± 1.3 years; height: 166.9 ± 7.2 cm; body mass: 64.4 ± 7.4 kg) volunteered to participate in the study. All participants completed two separate testing sessions consisting of two maximal bilateral and unilateral repetitions respectively of the isometric long-lever bridge performed at a knee angle of 30° degrees. All data were analyzed to assess the limb symmetry index (LSI) between testing procedures at 50-, 100-, 150-, 200-, 250 ms and at peak force (N). Results: Large differences in variance were observed within and between unilateral and bilateral tasks, particularly for rapid force and peak force asymmetry measures, as revealed by principal component analysis. Fair to slight agreement was observed between unilateral and bilateral assessment methods (k = 0.05 – 0.24) and large to very large relationships were observed between early force (≤ 100 ms) and late force (150-, 200- and 250 ms) within the same assessment category. Conclusions: These findings suggest that asymmetries assessed bilaterally do not carry over well to asymmetries assessed unilaterally, therefore displaying poor convergent validity. Furthermore, rapid asymmetry measures (asymmetries within 250 ms) and peak asymmetry measures (maximum during the trial) appear to demonstrate differing constructs.
Keywords
Force plates, hamstring asymmetries, isometric strength, principal component analysis
Document Type
Journal Article
Date of Publication
1-1-2026
Publication Title
Journal of Science in Sport and Exercise
Publisher
Springer
School
School of Medical and Health Sciences
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Comments
Sundh, A. E., Ripley, N. J., Lamb, A. J., Cantwell, C. J., & Comfort, P. (2026). Influence of isometric hamstring assessment modality: Asymmetries across bilateral and unilateral testing procedures. Journal of Science in Sport and Exercise. Advance online publication. https://doi.org/10.1007/s42978-025-00356-6