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ASBMR, Anual Meeting 2011, San Diego, 2011;

Correlation of Different Muscle Function Tests in Older Adults

Year: 2011

Buehring B, Fidler E, Krueger D, Binkley N
University of Wisconsin, Madison, WI


Evidence is growing that sarcopenia is an independent risk factor for falls and osteoporotic fractures. Definition of sarcopenia based on mass alone is not ideal as muscle function appears to better predict outcomes (e.g., disability, morbidity and mortality) than does muscle mass. As such, proposed sarcopenia definitions have included both measures of muscle mass and muscle function. To this end, this study aim was to examine the retest reliability of muscle function tests, specifically jumping mechanography (JM) in older adults and compare this method with established approaches and appendicular lean mass (ALM).
Community dwelling individuals age . 70 years performed muscle function tests including the short physical performance battery (SPPB), grip strength and JM. JM used maximal countermovement jumps performed on a force plate; force was recorded and body weight corrected peak power and jump height calculated. Total body DXA was used to assess ALM. ALM/height2 was used for comparison to muscle function tests. JM and SPPB were performed at three visits over time (screening, baseline, and two weeks) to examine reliability over time. Associations between muscle function tests and with ALM/height2 were evaluated using linear regression analysis. Repeated measures ANOVA, intraclass correlation (ICC) and coefficient of variation (CV) were used to examine retest reliability.
97 individuals (49 females and 48 males, mean age 80.7, range 70 . 95 years) with and without osteoporosis and sarcopenia participated. Muscle function testing was generally well tolerated; no participant sustained a JM or other test related injury. R2 values from regression analyses varied between muscle tests and ALM/height2. For example, jump power and grip strength were highly correlated (R2 = 0.44) while gait speed and chair-rise correlated less well (R2 = 0.15). ALM/height2 was unrelated to total SPPB, but highly correlated (R2 = 0.47) with grip strength. Repeated measures ANOVA did not show significant differences over time for jump power but found differences for gait speed and chair rise time. Jump power and jump height had excellent ICCs (0.94 and 0.89 respectively). CV was 6.8% for jump power and 13.5% for jump height. ICC and CV for SPPB components varied among tests (ICC: 0.68 for total SPPB score to 0.86 for repeated chair rise time, CV: 9.5% for gait speed to 10.8% for repeated chair rise time).
In older adults with and without sarcopenia JM appears to have excellent retest reliability, is stable over time (i.e., no learning effect is apparent), and can be performed safely. In this study, retest reliability of JM and its correlation with other muscle function tests and ALM/height2 was comparable to grip strength and possibly better than measures included in the SPPB. JM is a promising tool for muscle power assessment in older adults. Comparison of this approach with classical function assessment tools in longitudinal interventional studies is needed.

GID: 2727; Last update: 09.09.2011