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The Validity and Reliability of a Customized Rigid Supportive Harness During Smith Machine Back Squat Exercise

Scott, Brendan R.1; Dascombe, Ben J.1,2; Delaney, Jace A.1; Elsworthy, Nathan1; Lockie, Robert G.1; Sculley, Dean V.2,3; Slattery, Katie M.1,4

Journal of Strength & Conditioning Research:
doi: 10.1519/JSC.0b013e3182a362df
Original Research
Abstract

Abstract: Scott, BR, Dascombe, BJ, Delaney, JA, Elsworthy, N, Lockie, RG, Sculley, DV, and Slattery, KM. The validity and reliability of a customized rigid supportive harness during Smith machine back squat exercise. J Strength Cond Res 28(3): 636–642, 2014—Although the back squat exercise is commonly prescribed to both athletic and clinical populations, individuals with restricted glenohumeral mobility may be unable to safely support the bar on the upper trapezius using their hands. The aims of this study were to investigate the validity and reliability of a back squat variation using a rigid supportive harness that does not require unrestricted glenohumeral mobility for quantifying 1 repetition maximum (1RM). Thirteen young men (age = 25.3 ± 4.5 years, height = 179.2 ± 6.9 cm, and body mass = 86.6 ± 12.0 kg) with at least 2 years resistance training experience volunteered to participate in the study. Subjects reported to the lab on 3 occasions, each separated by 1 week. During testing sessions, subjects were assessed for 1RM using the traditional back squat (session 1) and harness back squat (HBS; sessions 2 and 3) exercises. Mean 1RM for the traditional back squat, and 2 testing sessions of the HBS (HBS1 and HBS2) were 148.4 ± 25.0 kg, 152.5 ± 25.7 kg, and 150.4 ± 22.6 kg, respectively. Back squat and mean HBS 1RM scores were very strongly correlated (r = 0.96; p < 0.001). There were no significant differences in 1RM scores between the 3 trials. The test-retest 1RM scores with the HBS demonstrated high reliability, with an intraclass correlation coefficient of 0.98 (95% confidence interval [CI] = 0.93–0.99), and a coefficient of variation of 2.6% (95% CI = 1.9–4.3). Taken together, these data suggest that the HBS exercise is a valid and reliable method for assessing 1RM in young men with previous resistance training experience and may be useful for individuals with restricted glenohumeral mobility.

Author Information

1Applied Sport Science and Exercise Testing Laboratory, Faculty of Science and Information Technology, University of Newcastle, Ourimbah, Australia;

2Priority Research Center in Physical Activity and Nutrition, University of Newcastle, Callaghan, Australia;

3Biomedical Sciences and Pharmacy, Faculty of Health, University of Newcastle, Ourimbah, Australia; and

4New South Wales Institute of Sport, Sydney Olympic Park, Sydney, Australia

Address correspondence to Brendan R. Scott, brendan.scott@uon.edu.au

Copyright © 2014 by the National Strength & Conditioning Association.