Reliability of isokinetic and isometric measurement of leg strength on men with mental retardation.

Abstract

The purpose of this study was to determine the reliability of isokinetic and isometric measurement of strength for tests of knee extension and hip abduction on men with mental retardation (MR). In addition, the relationships between isokinetic measures of peak torque (PT) and total work (TW) and isometric peak torque were examined. Twenty-two men with mild to moderate MR were tested for isokinetic knee extension and hip abduction strength on a Musculoskeletal, Evaluation, Rehabilitation and Conditioning (MAREC) systems dynamometer at velocities of 60 and 30 degrees/sec, respectively. Isometric peak torque was determined by an examiner using a Nicholas Manual Muscle Tester (NMMT). Intrarater correlation coefficients for the isokinetic PT and TW scores ranged from .97 to .99, whereas coefficients for isometric NMMT scores ranged from .97 to .98. Pearson correlation coefficients between PT and TW scores ranged from .76 to .93. Coefficients between isokinetic and isometric scores ranged from .43 to .73. These results indicate that highly reliable isokinetic and isometric measurements can be obtained on men with MR. Also, the relatively simple measurement of PT may be the isokinetic parameter of choice at the clinical setting. Moderate relationships between NMMT and isokinetic scores were found, indicating that the generalization of test scores from one test modality to another is not warranted.