The role of starting knee angle in squat jump force-velocity profiles: interactions with subjects` strength levels and imputed push-off distance

Introduction: This study investigated whether differences in the force-velocity (F-v) profile obtained using Samozino`s method during squat jumps (SJ) performed at varying knee angles are influenced by subjects` strength levels and the push-off distance (HpO) used in the analysis. Methods: Twenty-one resistance-trained men were classified as stronger (n = 10) or weaker (n = 11) based on the external load required to achieve a 10 cm SJ height. F-v profiles were randomly assessed over three sessions, with SJs performed at starting knee angles of 70° (SJ70), 90° (SJ90), and 110° (SJ110), using either the actual HpO specific to each condition or a standardized HpO corresponding to SJ90. Results: Significant differences between SJ types were observed for maximum force (F0) and the F-v slope (SJ110 > SJ90 > SJ70). These differences were never influenced by subjects` strength levels. The standardized HpO produced similar outcomes for maximum power (Pmax) and maximum velocity (v0), and more consistent results for F0 and the F-v slope compared to the actual HpO. Discussion: Regardless of strength levels, standardizing HpO at 90° and allowing subjects to select a starting knee angle between 70° and 90° could simplify the evaluation process and improve the comparability of F-v profiles across subjects when using Samozino`s method.
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Bibliographic Details
Subjects:
Notations:training science
Tagging:Kinematik
Published in:Frontiers in Physiology
Language:English
Published: 2025
Online Access:https://doi.org/10.3389/fphys.2025.1551488
Volume:16
Pages:1551488
Document types:article
Level:advanced