Normalization of rapid force to peak force in an isometric hamstring assessment using force plates

Barber, R.; Fahey, J.T.; Comfort, P.; Ripley, N.J.

Abstract

Purpose The aim of this investigation was to determine the reliability of normalizing rapid force (RF) production to peak force assessed during an isometric knee flexor assessment, and to present a novel method of classifying athletes' potential training needs within the 90–90 isometric hamstring assessment. Procedures Twenty elite female soccer players (age: 20.7 ± 4.7 years; height: 168.2 ± 5.5 cm; body mass: 62.8 ± 7.0 kg), with no recent (>6 months) history of hamstring strain injury, volunteered to participate in the study. Following a standardized warm-up, each participant performed three maximal isometric hamstring contractions, with their heel resting on a force plate, elevated on a box, to ensure that their hips and knees were at 90° Data was analyzed to determine peak for (PF), RF was established as force expressed at 100 ms (F100) and force expressed at 200 ms (F200), with force at each time-point subsequently normalized to a percentage of PF. Findings F100 and F200 normalized to PF demonstrated good absolute reliability (%CV = 6.12–7.62) and moderate relative reliability (ICC = 0.689–0.703). Concurrently observing PF and normalized F100 and F200 could provide clear training and monitoring goals. Conclusions Normalizing measures of RF production, including F100 and F200, to PF can be performed reliability. Therefore, could be tracked overtime to identify changes as an effect of training or for fatigue monitoring purposes. However, further research is required to determine how knee flexor force-time characteristics change in relation to focused training and how these characteristics change in response to fatiguing activities.

Citation

Barber, R., Fahey, J., Comfort, P., & Ripley, N. (2024). Normalization of rapid force to peak force in an isometric hamstring assessment using force plates. Apunts Sports Medicine, 59(223), 100450. https://doi.org/10.1016/j.apunsm.2024.100450

• Journal Article Type: Article
• Acceptance Date: Jun 5, 2024
• Online Publication Date: Jun 22, 2024
• Publication Date: Jun 22, 2024
• Deposit Date: Jun 24, 2024
• Publicly Available Date: Jun 26, 2024
• Journal: Apunts Sports Medicine
• Print ISSN: 2666-5069
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 59
• Issue: 223
• Pages: 100450
• DOI: https://doi.org/10.1016/j.apunsm.2024.100450