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Kinetics and Kinematics of the Squat and Step-up in Well-Trained Rugby Players

Appleby, Brendyn B.1,2; Newton, Robert U.1,3; Cormack, Stuart J.4

The Journal of Strength & Conditioning Research: January 30, 2019 - Volume Publish Ahead of Print - Issue - p
doi: 10.1519/JSC.0000000000003055
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Appleby, BB, Newton, RU, and Cormack, SJ. Kinetics and kinematics of the squat and step-up in well-trained rugby players. J Strength Cond Res XX(X): 000–000, 2018—The purpose of this study was to compare and contrast the kinetics and kinematics of squat and step-up performance in well-trained athletes. Triaxial ground reaction force (GRF) and 3D kinematic data were collected in 4 maximal effort repetitions each at 70, 80, and 90% of 1 repetition maximum (1RM) of squat and step-up. The difference in concentric phase kinetics and kinematics between the squat and step-up was compared using effect sizes (ES ± 90% confidence limits [CLs]) classified as: less than 0.2 as trivial; 0.2–0.6 as small; 0.6–1.2 as moderate; and 1.2–2.0 as large. Where the 90% CL crossed negative and positive 0.2 values, the effect was considered “unclear.n Ground reaction force was higher for the step-up than squat at all relative intensities per leg (peak GRF ES: 2.56 ± 0.19 to 2.70 ± 0.37; average GRF ES: 1.45 ± 0.27 to 1.48 ± 0.29). Per leg, the difference in concentric impulse favored the step-up compared with squat at 70% 1RM (ES = 0.71 ± 0.40) and 80% 1RM (ES = 0.30 ± 0.41) but was unclear at 90% 1RM (ES = −0.25 ± 0.47). The squat peak velocity was greater compared with step-up at all intensities (ES = −1.74 ± 0.48 to −1.33 ± 0.48). Despite a lower external load and a single base of support, per leg, the step-up produced comparable GRF because the squat suggesting overload provided by the step-up is sufficient for maximal strength development. Future research may investigate the efficacy of the step-up in a training intervention for the development of lower-body strength.

1School of Medical and Health Sciences, Edith Cowan University, Perth, Australia;

2High Performance Unit, Hockey Australia, Perth, Australia;

3School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Australia; and

4School of Exercise Science, Australian Catholic University, Melbourne, Australia

Address correspondence to Brendyn B. Appleby, brendyn.appleby@hockey.org.au.

Copyright © 2019 by the National Strength & Conditioning Association.