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Structure of force variability during squats performed with an inertial flywheel device under stable versus unstable surfaces
Moras, Gerard Vázquez-Guerrero, Jairo Fernández-Valdés, Bruno Rosas-Casals, Marti Weakley, Jonathon Jones, Ben Sampaio, Jaime
Moras, Gerard
Vázquez-Guerrero, Jairo
Fernández-Valdés, Bruno
Rosas-Casals, Marti
Weakley, Jonathon
Jones, Ben
Sampaio, Jaime
Abstract
The use of unstable surfaces during resistance training has demonstrated a maintenance or reduction on force production. However, the use of unstable surface on force variability has not been assessed using non-linear methods that may be better suited to detect changes in movement variability throughout a given movement. Consequently, this study compared the use of stable vs unstable surfaces on force variability during bilateral squats performed with an inertial flywheel device (Eccoteck, Byomedic System SCP, Spain). Twenty healthy men (mean ± SD: age 22.9 ± 2.9 years, height 1.81 ± 0.7 m, body mass 76.4 ± 7.6 kg and 1RM back squat 110.9 ± 19.7 kg) with a minimum of four years in resistance training performed six sets of six repetitions of squats at maximal concentric effort with one minute rest between sets. Force output on the vertical axes was measured using a strain gauge and the results were processed using non-linear sample entropy (SampEn). Results showed no differences for any of the dependent variables between stable and unstable conditions. SampEn showed no differences between conditions (chi-squared = 0.048 P = 0.827), while Forcemean and SampEn presented a small correlation (r = 0.184; p < 0.01). No changes in entropy were found over the course of the series. Together, these results suggest that the structure of force variability between stable and unstable surfaces are similar. This lack of difference between surfaces may be due to postural and anticipatory adjustments. Consequently, by introducing unstable surfaces to the flywheel bilateral squat exercise, practitioners may not observe changes in Forcemean and force variability when compared to stable surface training suggesting that increased training volumes or intensity may be required during unstable environments to cause a desired training stimulus.
Keywords
Sample entropy, Resistance training, Strength training, Performance analysis, Eccentric, Instability
Date
2019
Type
Journal article
Journal
Human Movement Science
Book
Volume
66
Issue
Page Range
497-503
Article Number
ACU Department
School of Behavioural and Health Sciences
Faculty of Health Sciences
Faculty of Health Sciences
Relation URI
Source URL
Event URL
Open Access Status
License
File Access
Controlled