David R Clark1, Michael I Lambert2, Chris Grigson3, Angus M Hunter3. 1. School of Sport and Exercise Sciences, Faculty of Science, Liverpool John Moore's University, Liverpool, UK. d.r.clark@ljmu.ac.uk. 2. Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa. 3. Physiology, Exercise and Nutrition Research Group, Faculty of Health Sciences and Sport, University of Stirling, Stirling, UK.
Abstract
PURPOSE: In this study we measured neural activation (EMG) in four trunk stabilizer muscles and vastus lateralis (VL) in trained and novice participants during a set of squat repetitions to volitional fatigue at 85% 1RM. METHODS: Forty males were recruited into two groups, novice (NG: n = 21) and experienced (EG: n = 19), according to relative squat 1RM. Participants were tested twice to: (1) determine squat 1RM, and (2) complete a single set of repetitions to volitional fatigue at 85% 1RM. Relative squat 1RM; NG < 140% body mass, EG > 160% body mass. Neuromuscular activation was measured by EMG for the following: rectus abdominus (RA), external oblique (EO), lumbar sacral erector spinae (LSES), upper lumbar erector spinae (ULES) and VL in eccentric and concentric phase. Completed repetitions, RPE and EMG in repetition 1 and at 20, 40, 60, 80 and 100% of completed repetitions were analysed. RESULTS: No group differences were found between number repetitions completed and RPE in repetitions to volitional fatigue at 85% 1RM. Neuromuscular activation increased significantly in all muscle groups in eccentric and concentric phase apart from RA in the eccentric phase. Trunk neuromuscular activation was higher in NG compared to EG and this was significant in EO, LSES and ULES in eccentric phase and LSES in the concentric phase. VL activation increased in both phases with no group differences. CONCLUSION: Trunk neuromuscular activation increases in a fatiguing set of heavy squats regardless of training status. Increased back squat strength through training results in lower neuromuscular activation despite greater absolute external squat loads.
PURPOSE: In this study we measured neural activation (EMG) in four trunk stabilizer muscles and vastus lateralis (VL) in trained and novice participants during a set of squat repetitions to volitional fatigue at 85% 1RM. METHODS: Forty males were recruited into two groups, novice (NG: n = 21) and experienced (EG: n = 19), according to relative squat 1RM. Participants were tested twice to: (1) determine squat 1RM, and (2) complete a single set of repetitions to volitional fatigue at 85% 1RM. Relative squat 1RM; NG < 140% body mass, EG > 160% body mass. Neuromuscular activation was measured by EMG for the following: rectus abdominus (RA), external oblique (EO), lumbar sacral erector spinae (LSES), upper lumbar erector spinae (ULES) and VL in eccentric and concentric phase. Completed repetitions, RPE and EMG in repetition 1 and at 20, 40, 60, 80 and 100% of completed repetitions were analysed. RESULTS: No group differences were found between number repetitions completed and RPE in repetitions to volitional fatigue at 85% 1RM. Neuromuscular activation increased significantly in all muscle groups in eccentric and concentric phase apart from RA in the eccentric phase. Trunk neuromuscular activation was higher in NG compared to EG and this was significant in EO, LSES and ULES in eccentric phase and LSES in the concentric phase. VL activation increased in both phases with no group differences. CONCLUSION: Trunk neuromuscular activation increases in a fatiguing set of heavy squats regardless of training status. Increased back squat strength through training results in lower neuromuscular activation despite greater absolute external squat loads.
Entities:
Keywords:
Back squat; Electromyography; Neuromuscular; Strength training; Trunk stabilizers
Authors: Eric L Dugan; Tim L A Doyle; Brendan Humphries; Christopher J Hasson; Robert U Newton Journal: J Strength Cond Res Date: 2004-08 Impact factor: 3.775
Authors: Tomoko Shimano; William J Kraemer; Barry A Spiering; Jeff S Volek; Disa L Hatfield; Ricardo Silvestre; Jakob L Vingren; Maren S Fragala; Carl M Maresh; Steven J Fleck; Robert U Newton; Luuk P B Spreuwenberg; Keijo Häkkinen Journal: J Strength Cond Res Date: 2006-11 Impact factor: 3.775
Authors: Gregory D Myer; Adam M Kushner; Jensen L Brent; Brad J Schoenfeld; Jason Hugentobler; Rhodri S Lloyd; Al Vermeil; Donald A Chu; Jason Harbin; Stuart M McGill Journal: Strength Cond J Date: 2014-12-01 Impact factor: 2.143
Authors: Randall F Gearhart; Fredric L Goss; Kristen M Lagally; John M Jakicic; Jere Gallagher; Kara I Gallagher; Robert J Robertson Journal: J Strength Cond Res Date: 2002-02 Impact factor: 3.775