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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| Notations: | training science |
| Tagging: | Kinematik |
| Published in: | Frontiers in Physiology |
| Language: | English |
| Published: |
2025
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| Online Access: | https://doi.org/10.3389/fphys.2025.1551488 |
| Volume: | 16 |
| Pages: | 1551488 |
| Document types: | article |
| Level: | advanced |