The Role of Starting Knee Angle in Squat Jump Force-velocity Profiles: Interactions with Subjects' Strength Levels and Imputed Push-off Distance

Overview

Journal Front Physiol

Date 2025 Feb 27

PMID 40013241

Authors

Xuelin Qin

Beibei Liu

Ruolin Tang

Yan Liu

Amador Garcia-Ramos

Affiliations

Soon will be listed here.

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 ( ) 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) and maximum velocity ( ), and more consistent results for 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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