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

BACKGROUND: The objective of this study was to assess the reliability of a hand-held dynamometer for isometric strength measurements among nursing home residents. METHODS: The 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 4 days by the same operator and after 8 days 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. RESULTS: Thirty nursing home residents (75.0 +/- 11.2 years, 50% of women) were enrolled in this study. ICC of the test-retest with one single operator ranged from 0.60 (0.37-0.83) for the ankle extensors to 0.85 (0.74-0.95) for the elbow flexors. When considering the test-retest with two different operators, the ICC values ranged from 0.62 (0.41-0.84) for the ankle extensors to 0.87 (0.79-0.96) for the elbow extensors. For the absolute reliability, MDC% varies from 27.64 (elbow flexors) to 81.97 (ankle extensors) when performed in intra-observer. In interobserver condition, MDC%, respectively, varies from 24.38 (elbow extensors) 67.59 (ankle extensors). CONCLUSION: Using 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.