Reliability of isometric lower-extremity muscle strength measurements in children with cerebral palsy: implications for measurement design.

Background: Children with cerebral palsy (CP) typically show muscle weakness of the lower extremities, which can be measured with the use of handheld dynamometry (HHD).

Objective: The purposes of this study were: (1) to determine test-retest reliability and measurement error of isometric lower-extremity strength measurements in children with CP with the use of HHD and (2) to assess implications for measurement design.

Design: A test-retest design was used.