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In vivo fascicle length measurements via B-mode ultrasound imaging with single vs dual transducer arrangements

Brennan, SF, Cresswell, AG, Farris, DJ and Lichtwark, GA (2017) In vivo fascicle length measurements via B-mode ultrasound imaging with single vs dual transducer arrangements. Journal of Biomechanics, 64. pp. 240-244. ISSN 0021-9290

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Abstract

Ultrasonography is a useful technique to study muscle contractions in vivo, however larger muscles like vastus lateralis may be difficult to visualise with smaller, commonly used transducers. Fascicle length is often estimated using linear trigonometry to extrapolate fascicle length to regions where the fascicle is not visible. However, this approach has not been compared to measurements made with a larger field of view for dynamic muscle contractions. Here we compared two different single-transducer extrapolation methods to measure VL muscle fascicle length to a direct measurement made using two synchronised, in-series transducers. The first method used pennation angle and muscle thickness to extrapolate fascicle length outside the image (extrapolate method). The second method determined fascicle length based on the extrapolated intercept between a fascicle and the aponeurosis (intercept method). Nine participants performed maximal effort, isometric, knee extension contractions on a dynamometer at 10° increments from 50 to 100° of knee flexion. Fascicle length and torque were simultaneously recorded for offline analysis. The dual transducer method showed similar patterns of fascicle length change (overall mean coefficient of multiple correlation was 0.76 and 0.71 compared to extrapolate and intercept methods respectively), but reached different absolute lengths during the contractions. This had the effect of producing force–length curves of the same shape, but each curve was shifted in terms of absolute length. We concluded that dual transducers are beneficial for studies that examine absolute fascicle lengths, whereas either of the single transducer methods may produce similar results for normalised length changes, and repeated measures experimental designs.

Item Type: Article
Uncontrolled Keywords: 0903 Biomedical Engineering, 1106 Human Movement and Sports Sciences, 0913 Mechanical Engineering
Subjects: R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Sport & Exercise Sciences
Publisher: Elsevier
Date Deposited: 12 Mar 2019 09:53
Last Modified: 13 Mar 2019 11:25
DOI or Identification number: 10.1016/j.jbiomech.2017.09.019
URI: http://researchonline.ljmu.ac.uk/id/eprint/10291

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