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Test–retest reliability of isokinetic concentric knee extension and flexion
  1. E Cockburn1,
  2. P Hayes2
  1. 1Department of Sport Development, Management and Coaching, Northumbria University, Newcastle upon Tyne, UK
  2. 2Department of Sport and Exercise Science, Northumbria University, Newcastle upon Tyne, UK


Isokinetic dynamometry, which is a useful tool for the assessment of muscular function, must have sufficient reliability to be certain that changes are due to experimental intervention. Isokinetic concentric knee extension and flexion measured with a range of dynamometers has high reliability, but differences in measured variables exist between different dynamometers. Therefore, the aim of this study was to determine the reliability of isokinetic concentric knee extension and flexion on a Cybex Norm. Following familiarisation, 14 participants (23±3 years; 171±9 cm; 65.9±9.6 kg) attended the laboratory on 3 separate occasions, separated by 1 week. On each visit, participants completed 6 maximal concentric knee extension/flexions at 1.05 rad/s on a Cybex Norm Isokinetic Dynamometer. Reliability was assessed using intraclass correlation coefficients (ICC) and group coefficients of variation (CV). CV's for peak torque were 4.0%, 5.1%, 4.9% and 4.5% for dominant quadriceps, nondominant quadriceps, dominant hamstrings and nondominant hamstrings, respectively. ICC's for peak torque of each measurement ranged from 0.82 to 0.97. The results demonstrate that the protocol and dynamometer used are reliable measures of concentric peak torque of the knee extensors and flexors, and are in line with other data examining isokinetic dynamometry.

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