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Original Articles

Effects of verbal knee alignment instructions on knee kinematics, kinetics and the performance of a single-leg jump in female adolescent soccer players

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Pages 106-114 | Received 19 Jun 2018, Accepted 08 Dec 2018, Published online: 22 Feb 2019
 

Abstract

Background: Little is known about the effects of verbal instructions on the technique and performance of sports-related tasks. The aim of this study was therefore to investigate the acute effects of knee alignment instructions on knee kinematics and the performance of a single-leg jump in female adolescent soccer players.

Methods: Twenty-eight adolescent female soccer players completed three blocks of 15 single-leg jumps. The participants were randomised to an experimental group receiving verbal instructions focussing on proper knee alignment (the avoidance of knee valgus) or to a control group only receiving instructions on task execution. Outcomes were knee kinematics (flexion and valgus angles) and jump performance (number of incorrect trials and contact time).

Results: The experimental group demonstrated 36% less knee valgus and 11–13% greater knee flexion compared to the control group. While jump performance remained unchanged in the experimental group over the course of the experiment, the control group demonstrated a 20% decrease in the number of incorrect trials and a 25% reduction in contact time over the course of the experiment.

Conclusions: The present results indicate that verbal instructions accentuating proper knee alignment benefit knee kinematics but not jump performance in adolescent female soccer athletes.

Acknowledgements

The authors would like to thank the participants and the physiotherapy students who were involved in this project for their time and energy.

Disclosure statement

No potential conflict of interest was reported by the authors.