Reliability of muscle strength measures obtained with a hand-held dynamometer in an elderly population

BackgroundThe objective of this study was to assess the reliability of a hand-held dynamometer for isometric strength measurements among nursing home residents. MethodsThe isometric muscle strength of nursing home residents was assessed for eight different muscle groups, using a hand-held dynamometer, the MicroFET2 device. Strength measurements were performed at baseline and after 4days by the same operator and after 8days by a second operator. Intraclass coefficients (ICC) were computed to assess the relative reliability, whereas the minimal detectable change (MDC%) was calculated to assess the absolute reliability of the test-retest of the MicroFET2 used by one single operator or by two different ones. ResultsThirty nursing home residents (750112years, 50% of women) were enrolled in this study. ICC of the test-retest with one single operator ranged from 060 (037-083) for the ankle extensors to 085 (074-095) for the elbow flexors. When considering the test-retest with two different operators, the ICC values ranged from 062 (041-084) for the ankle extensors to 087 (079-096) for the elbow extensors. For the absolute reliability, MDC% varies from 2764 (elbow flexors) to 8197 (ankle extensors) when performed in intra-observer. In interobserver condition, MDC%, respectively, varies from 2438 (elbow extensors) 6759 (ankle extensors). ConclusionUsing standardized protocol and standardized instructions to patients, a high relative and moderate absolute reliability was observed for all but ankle muscle groups, making this hand-held dynamometer a potential tool for research in the elderly population.