CC BY-NC-ND 4.0 · Sports Med Int Open 2020; 4(02): E59-E66
DOI: 10.1055/a-1195-1039
Training & Testing

Kinematic and EMG Comparison Between Variations of Unilateral Squats Under Different Stabilities

Roland van den Tillaar
1   Department of Sports Sciences and Physcial Education, Nord University, Levanger, Norway
,
Stian Larsen
1   Department of Sports Sciences and Physcial Education, Nord University, Levanger, Norway
› Author Affiliations

Abstract

The purpose of the study was to compare kinematics and muscle activity between two variations of unilateral squats under different stability conditions. Twelve male volunteers (age: 23±5 years, mass: 80±17 kg, height: 1.81±0.11 m, strength-training experience: 4.3±1.9 years) performed four repetitions with the same external load (≈4RM). Two variations (with the non-stance leg forwards vs. backwards) were performed in a Smith-machine and free-weight condition. The variables were barbell velocity, lifting time and surface electromyography activity of the lower extremity and trunk muscles during the descending and ascending phase. The main findings were 1) peak force was higher when performing the unilateral squats in the Smith machine; 2) peak ascending barbell velocity increased from repetition 3–4 with free weight; and 3) muscle activity from the rectus femoris, vastus lateral, biceps femoris, gluteus medius, and erector spinae increased with repetitions, whereas gluteus, and medial vastus and shank muscles were affected by the conditions. It was concluded that more peak force could be produced because of increased stability. However, peak barbell velocity increased from repetition to repetition in free-weight unilateral squats, which was probably because the participants grew more comfortable. Furthermore, increased instability causes more gluteus and vastus medial activation and foot variations mainly affected the calf muscles.



Publication History

Received: 07 April 2020
Received: 02 June 2020

Accepted: 05 June 2020

Article published online:
16 July 2020

© 2019. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).

© Georg Thieme Verlag KG
Stuttgart · New York

 
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