Sources of Variability in Musculo-Articular Stiffness Measurement

Author(s)
Ditroilo, Massimiliano
Watsford, Mark
Murphy, Aron
de Vito, Giuseppe
Publication Date
2013
Abstract
The assessment of musculo-articular stiffness (MAS) with the free-oscillation technique is a popular method with a variety of applications. This study examined the sources of variability (load applied and frequency of oscillation) when MAS is assessed. Over two testing occasions, 14 healthy men (27.7±5.2 yr, 1.82±0.04 m, 79.5±8.4 kg) were measured for isometric maximum voluntary contraction and MAS of the knee flexors using submaximal loads relative to the individual's maximum voluntary contraction (MAS%MVC) and a single absolute load (MASABS). As assessment load increased, MAS%MVC (coefficient of variation (CV) = 8.1-12.1%; standard error of measurement (SEM) = 51.6-98.8 Nm-1) and frequency (CV = 4.8-7.0%; SEM = 0.060-0.075 s-1) variability increased consequently. Further, similar levels of variability arising from load (CV = 6.7%) and frequency (CV = 4.8-7.0%) contributed to the overall MAS%MVC variability. The single absolute load condition yielded better reliability scores for MASABS (CV = 6.5%; SEM = 40.2 Nm-1) and frequency (CV = 3.3%; SEM = 0.039 s-1). Low and constant loads for MAS assessment, which are particularly relevant in the clinical setting, exhibited superior reliability compared to higher loads expressed as a percentage of maximum voluntary contraction, which are more suitable for sporting situations. Appropriate sample size and minimum detectable change can therefore be determined when prospective studies are carried out.
Citation
PLoS One, 8(5), p. 1-5
ISSN
1932-6203
Link
Publisher
Public Library of Science
Title
Sources of Variability in Musculo-Articular Stiffness Measurement
Type of document
Journal Article
Entity Type
Publication

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