VP.28 Psychometric properties of muscle strength assessment by hand-held dynamometry in healthy adults: A reliability study

Abstract

Maximal isometric muscle strength (MIMS) assessment is a key component of physiotherapist' work. Hand-held dynamometry (HHD) is a simple and quick method to obtain quantified MIMS values. However, the lack of MIMS reference values with well-known psychometric properties in healthy adults limits the use and the interpretation of the measures obtained with HHD in clinic. To determine the intra- and inter-rater reliability, standard error of measurement (SEM) and minimal detectable changes (MDC) of MIMS values obtained with HHD. MIMS measurements of 17 muscle groups were assessed by two independent raters at three different times in 30 healthy adults aged between 18 and 70 years old using a standardized HHD protocol: T1(day 1: rater 1), T2 (day 5: rater 2) and T3 (day 14: rater 1). Intra- and inter-rater reliability were measured using intra-class correlation coefficients (ICC: 95% confidence interval) and the SEM and MDC were calculated from these reliability data. Intra-rater reliability and inter-rater reliability were good to excellent with ICC (95% confidence interval) varying from 0,90 to 0,99 (0,85-0,99) and 0,89 to 0,99 (0,55-0,995) respectively, except for the wrist flexors and the internal hip rotators, which showed moderate to excellent inter-rater reliability. Relative and absolute SEM and MDC for intra-rater reliability ranged from 0.14 to 3.20 Nm and 0.50 to 3.45 % for the SEM and 0.38 to 8.87 Nm and 1.38 to 7.88% for the MDC, respectively for all muscle groups. Relative and absolute SEM and MDC for inter-rater reliability ranged from 0.17 to 5.80 Nm and 0.49 to 3.25 % for the SEM and 0.47 to 16.06 Nm and 1.35 to 9.02% for the MDC, respectively. The good to excellent intra- and inter-rater reliability of the standardized HHD protocol make of the HHD protocol used a method of choice in clinical or research setting. Knowing the psychometric properties of MIMS values obtained with HHD standardized measurement protocols will allow an optimal use of the reference values established. Hand-held dynamometry, muscle strength, psychometric properties, quantitative evaluation.