The Effect of Initial Knee Angle on Concentric-Only Squat Jump Performance. Issue 2 (3rd April 2017)

• Record Type: Journal Article
• Authors: Mitchell, Lachlan J.; Argus, Christos K.; Taylor, Kristie-Lee; Sheppard, Jeremy M.; Chapman, Dale W.
• Is Part Of: Research quarterly for exercise and sport. Volume 88:Issue 2(2017)
• Page Start: 184
• Page End: 192
• Publication Date: 2017-04-03
• Subjects: Concentric-only jump -- knee angle -- relative net impulse -- squat depth; Physical education and training -- Periodicals; Health education -- Periodicals; Recreation -- Periodicals; Physical Education and Training -- Periodicals; Sports -- Periodicals; Exercise -- Periodicals; Education -- Periodicals; Lichamelijke opvoeding; Sport; Exercice -- Périodiques; Sports -- Périodiques; 613.7105
• DOI: 10.1080/02701367.2017.1293777
• Languages: English
• ISSNs: 0270-1367

Abstract

ABSTRACT: Purpose : There is uncertainty as to which knee angle during a squat jump (SJ) produces maximal jump performance. Importantly, understanding this information will aid in determining appropriate ratios for assessment and monitoring of the explosive characteristics of athletes.Method : This study compared SJ performance across different knee angles—90º, 100º, 110º, 120º, 130º, and a self-selected depth—for jump height and other kinetic characteristics. For comparison between SJ and an unconstrained dynamic movement, participants also performed a countermovement jump from a self-selected depth. Thirteen participants ( M age = 25.4 ± 3.5 years, M height = 1.8 ± 0.06 m, M weight = 79.8 ± 9.5 kg) were recruited and tested for their SJ performance.Results : In the SJ, maximal jump height (35.4 ± 4.6 cm) was produced using a self-selected knee angle (98.7 ± 11.2°). Differences between 90°, 100°, and self-selected knee angles for jump height were trivial (ES ± 90% CL = 90°–100° 0.23 ± 0.12, 90°–SS −0.04 ± 0.12, 100°–SS −0.27 ± 0.20; 0.5–2.4 cm) and not statistically different. Differences between all other knee angles for jump height ranged from 3.8 ± 2.0 cm (mean ± 90% CL) to 16.6 ± 2.2 cm. A similar outcome to jump height was observed for velocity, force relative to body weight, and impulse for the assessed knee angles.Conclusions : For young physically active adult men, the use of a self-selected depth in the SJ results in optimal performance and has only a trivial difference to a constrained knee angle of either 90° or 100°.