The Isometric Horizontal Push Test: Test-Retest Reliability and Validation Study.

Abstract

To investigate the test-retest reliability and criterion validity of the isometric horizontal push test (IHPT), a newly designed test that selectively measures the horizontal component of maximal isometric force. Twenty-four active males with ≥3 years of resistance training experience performed 2 testing sessions of the IHPT, separated by 3 to 4 days of rest. In each session, subjects performed 3 maximal trials of the IHPT with 3 minutes of rest between them. The peak force outputs were collected simultaneously using a strain gauge and the criterion equipment consisting of a floor-embedded force plate. The test-retest reliability of peak force values was nearly perfect (intraclass correlation coefficient = ∼.99). Bland-Altman analysis showed excellent agreement between days with nearly no bias for strain gauge 1.2N (95% confidence interval [CI], -3 to 6N) and force plate 0.8N (95% CI, -4 to 6N). A nearly perfect correlation was observed between the strain gauge and force plate (r = .98, P < .001), with a small bias of 8N (95% CI, 1.2 to 15N) in favor of the force plate. The sensitivity of the IHPT was also good, with smallest worthwhile change greater than standard error of measurement for both the strain gauge (smallest worthwhile change: 29N; standard error of measurement: 17N; 95% CI, 14 to 20N) and the force plate (smallest worthwhile change: 29N; standard error of measurement: 18N; 95% CI, 14 to 19N) devices. The high degree of validity, reliability, and sensitivity of the IHPT, coupled with its affordability, portability, ease of use, and time efficacy, point to the potential of the test for assessment and monitoring purposes.