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Kinetic Analysis of Isometric Back Squats and Isometric Belt Squats

Layer, Jacob S.1; Grenz, Christylynne1; Hinshaw, Taylour J.1; Smith, Derek T.1; Barrett, Steven F.2; Dai, Boyi1

The Journal of Strength & Conditioning Research: December 2018 - Volume 32 - Issue 12 - p 3301–3309
doi: 10.1519/JSC.0000000000002854
Original Research

Layer, JS, Grenz, C, Hinshaw, TJ, Smith, DT, Barrett, SF, and Dai, B. Kinetic analysis of isometric back squats and isometric belt squats. J Strength Cond Res 32(12): 3301–3309, 2018—Belt squats seem to provide an alternative to back squats. However, it is not clear how musculoskeletal loading differs between the two. This study compared lower extremity and low-back kinetics during isometric back squats and isometric belt squats. Sixteen men (age: 22.6 ± 3.4 years; height: 1.74 ± 0.11 m; mass: 82.0 ± 5.6 kg) and 10 women (age: 21.5 ± 2.5 years; height: 1.64 ± 0.10 m; mass: 68.9 ± 7.1 kg) performed isometric back squats and belt squats at 4 squat depths. Joint resultant moments were calculated from kinematic and ground reaction force data. Linear interpolation was used to estimate peak vertical forces and joint moments at a 45° thigh segment angle. Subjects increased peak forces, ankle moments, and knee moments but decreased low-back moments from back to belt squats (p ≤ 0.023). Hip moments did not significantly change between 2 squats. Subjects demonstrating smaller ankle and knee moments during back squats showed greater increases in these moments from back to belt squats (p ≤ 0.012, R 2 ≤ 0.24). Subjects whose back squats were characterized by greater low-back moments displayed greater decreases in low-back moments from back to belt squats (p < 0.001, R 2 = 0.98). Compared with isometric back squats, isometric belt squats may provide a similar or greater external loading for the musculoskeletal system of the lower extremities while reducing external spinal loading. Belt squats may be considered by individuals with upper-body or spinal injuries and those displaying excessive external back moments.

1Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming; and

2Department of Electrical and Computer Engineering, University of Wyoming, Laramie, Wyoming

Address correspondence to Boyi Dai, bdai@uwyo.edu.

Copyright © 2018 by the National Strength & Conditioning Association.