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

IF 3.2 3区医学 Q2 PHYSIOLOGY

Frontiers in Physiology Pub Date : 2025-02-12 eCollection Date: 2025-01-01 DOI:10.3389/fphys.2025.1551488

Xuelin Qin, Beibei Liu, Ruolin Tang, Yan Liu, Amador García-Ramos

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引用次数: 0

Abstract

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 (F ₀) 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 (P_max) and maximum velocity (v ₀), and more consistent results for F ₀ 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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来源期刊

Frontiers in Physiology PHYSIOLOGY-

CiteScore

6.50

自引率

5.00%

发文量

2608

审稿时长

14 weeks

期刊介绍： Frontiers in Physiology is a leading journal in its field, publishing rigorously peer-reviewed research on the physiology of living systems, from the subcellular and molecular domains to the intact organism, and its interaction with the environment. Field Chief Editor George E. Billman at the Ohio State University Columbus is supported by an outstanding Editorial Board of international researchers. This multidisciplinary open-access journal is at the forefront of disseminating and communicating scientific knowledge and impactful discoveries to researchers, academics, clinicians and the public worldwide.