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

The objective of this study was to assess the reliability of a hand-held dynamometer for isometric strength measurements among nursing home residents.

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.

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).

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.