RESEARCH REPORT POSTER DISPLAY

RELIABILITY AND VALIDITY OF HAND-HELD DYNAMOMETRY AND THE RELATIONSHIP BETWEEN LOWER EXTREMITY MUSCLE STRENGTH AND FUNCTIONAL TESTS IN OLDER ADULTS. Warkentin K, Arnold C, Chilibeck P, Magnus C, Skarpinsky L; University of Saskatchewan, Saskatoon SK, Canada

PURPOSE: 1) Evaluate intra-rater (same day and multiple day) reliability and inter-rater reliability of hand-held dynamometry (HHD). 2) Compare HHD to muscle strength measured by a standard isometric dynamometer (ID). 3) Determine the relationship of lower extremity muscle strength to balance, step length, rapid step, and lower extremity response time. RELEVANCE: HHD is a cost-efficient and convenient method of evaluating strength in older adults. In order for HHD to be a useful clinical tool, establishing its reliability and validity is essential. PARTICIPANTS: Eighteen adults (4 men, 14 women) ranging in age from 65 to 92, with or without lower extremity pain, without medical or neurological conditions affecting balance participated in this study. METHODS: Testing was performed on two occasions a maximum of 7 days apart. On the first day we tested strength using HHD and ID. Movements tested were hip abduction, hip flexion, hip extension, knee extension, and ankle dorsiflexion. Participants also performed the Modified Clinical Test of Sensory Interaction and Balance (MCTSIB), maximal step length (MSL), rapid step test (RST) and lower extremity response time (LERT). Inter-rater reliability (two independent testers) was assessed on Day 2. ID was performed only on Day 1 for the purpose of establishing validity of HHD strength testing. ANALYSIS: Intra-class correlation coefficients, standard error of measurement and descriptive statistics were used to verify reliability. Pearson r correlation coefficients were calculated to evaluate the relationship of hand-held dynamometry to the other tests. A p value of 0.05 was used for statistical significance. SPSS Version 14.0 was used for all statistical analyses. RESULTS: With the exception of one isolated measurement, ICC values for same day intra-rater reliability of HHD ranged from 0.84 to 0.99. For inter-rater reliability of HHD, ICC values ranged from 0.80 to 0.94 except for dorsiflexion (ICC 0.48 and 0.62). HHD also showed good multiple day intra-rater reliability with ICC values ranging from 0.76 to 0.94. Validity of HHD for all movements except dorsiflexion was confirmed by a significant correlation with ID showing Pearson correlation coefficients ranging from 0.55 to 0.84. There were no significant correlations between ID and RST time and error measurements. For the MCTSIB correlation with ID, all Pearson correlation coefficients were insignificant (r < 0.43) with the exception of left hip flexion (r = 0.50). For LERT, all movements except knee extension showed significant correlations with ID (r = 0.48 to 0.65). Similarly for MSL, all movements except left knee extension showed significant correlations with ID (r = 0.54 to 0.80). CONCLUSIONS: HHD is a reliable and valid assessment tool when measuring strength at the hip and knee in a small sample of older adults. Hip strength was associated with lower extremity response time and step length in this group. A larger sample size may be used in similar research in the future. IMPLICATIONS: HHD is a convenient and cost-efficient method of measuring muscle strength in older adults. Hip strength may be an important contributor to step length and response time which are important factors to prevent falls. KEYWORDS: reliability, validity, hand-held dynamometry. FUNDING ACKNOWLEDGEMENTS: University of Saskatchewan Summer Student Research Project program.

ETHICS COMMITTEE: University of Saskatchewan Biomedical Ethics Committee.