Reliability of quantitative muscle testing in healthy children and in children with Duchenne muscular dystrophy using a hand-held dynamometer.

The purpose of this study was to examine intratester and test-retest reliability using a hand-held dynamometer for the measurement of isometric muscle strength in 28 healthy children and children with Duchenne muscular dystrophy. The Dystrophic Group consisted of 14 children diagnosed with Duchenne muscular dystrophy, and the Healthy Group consisted of 14 age-matched children with no history of orthopedic or neuromuscular disorders. One physical therapist tested hip and knee extension, elbow flexion, and shoulder abduction in each child bilaterally. A two-way analysis of variance for repeated measures was used to analyze differences between measurements taken within and across the testing sessions. Pearson product-moment correlation coefficients were determined on mean values across the testing sessions for each variable. No significant differences (p greater than .05) between measurements taken within or across testing sessions were found in either the Dystrophic Group or the Healthy Group. Correlation coefficients for the Dystrophic Group ranged from .83 to .99 for the variables tested. Correlation coefficients for the Healthy Group ranged from .74 to .99. The results suggest that the hand-held dynamometer can be used as a reliable instrument in measuring the isometric strength of selected muscles in children.