Influence of Load and Phase of Contraction on Lateral Symmetries in Flywheel Squats

Darjan Smajla,Nejc Šarabon,Darjan Spudić

doi:10.3390/sym13010111

Abstract

Assessment of lateral symmetries (LS) of lower limbs has been widely investigated. However, there are no studies about LS during exposure to high eccentric and concentric loads during flywheel (FW) squats. A total of 422 young, physically active participants performed squats on an FW device with different equidistant loads (0.05, 0.125 and 0.2 kg∙m2). The mean and peak force of the left and right leg were assessed for the concentric and eccentric contaction phase. LS values were calculated for each load and phase of squat. Our results showed that the absolute mean and peak force of the concentric and eccentric phase of contraction had excellent reliability, while LS values were more reliable when eccentric force was used for their calculation. Mean and peak forces were increased with the higher FW load. In general, we found a decrease in LS values in the concentric phase of contraction with the higher load. Moreover, values of LS are similar to a wide range of other functional movements. Nevertheless, symmetrical force application during squatting on a FW device should be satisfied regardless of the FW load. Due to the large sample size, our results are valuable as a reference point when athletes are evaluated during training.

Highlights

In past years, differences in function and performance of the contralateral limbs have been widely investigated
Our results showed that the absolute mean and peak force of the concentric and eccentric phase of contraction had excellent reliability, while lateral symmetries (LS) values were more reliable when eccentric force was used for their calculation
We hypothesized that the mean and peak force would significantly increase with higher FW load, while significantly higher mean and peak forces would be present in the eccentric phase of contraction as compared to the concentric phase

Summary

Introduction

Differences in function and performance of the contralateral limbs have been widely investigated. Studies used different methods for quantifying lateral symmetry such as isokinetic dynamometry [1], free weights [2], jumping [3], and change of direction speed [4] None of these methods assessed lateral (a)symmetries by combining concentric and eccentric contraction under higher loads, which occur in sport-specific actions [5]. The decreased strength symmetries between the left and right side or dominant and non-dominant side, which are considered as a risk factor for injury ranging from 10 to 15% [7,8,9] These differences are more frequently evaluated in different unilateral tasks [10,11,12,13], while evaluation of bilateral resistance exercises during squatting is rare as bilateral exercises are most often incorrectly considered symmetrical [14]

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Results