The effect of muscle-tendon unit vs fascicle analyses on vastus lateralis force generating capacity during constant power output cycling with variable cadence

Brennan, Scott Francis, Cresswell, Andrew G., Farris, Dominic James and Lichtwark, Glen A. (2018) The effect of muscle-tendon unit vs fascicle analyses on vastus lateralis force generating capacity during constant power output cycling with variable cadence. Journal of Applied Physiology, . doi:10.1152/japplphysiol.00356.2017


Author Brennan, Scott Francis
Cresswell, Andrew G.
Farris, Dominic James
Lichtwark, Glen A.
Title The effect of muscle-tendon unit vs fascicle analyses on vastus lateralis force generating capacity during constant power output cycling with variable cadence
Journal name Journal of Applied Physiology   Check publisher's open access policy
ISSN 8750-7587
1522-1601
Publication date 2018-01-04
Year available 2018
Sub-type Article (original research)
DOI 10.1152/japplphysiol.00356.2017
Open Access Status Not yet assessed
Place of publication Bethesda, MD United States
Publisher American Physiological Society
Language eng
Abstract The maximum force capacity of a muscle is dependent on the lengths and velocities of its contractile apparatus. Muscle-tendon unit (MTU) length changes can be estimated from joint kinematics, however contractile element length changes are more difficult to predict during dynamic contractions. The aim of this study was to compare vastus lateralis (VL) MTU and fascicle force-length and force-velocity relationships, and dynamic muscle function while cycling at a constant submaximal power output (2.5 W/kg) with different cadences. We hypothesized that manipulating cadence would not affect VL MTU shortening, but significantly affect VL fascicle shortening. Furthermore, these differences would affect the predicted force capacity of the muscle. Using an isokinetic dynamometer and B-mode ultrasound (US), we determined the force-length and force-velocity properties of the VL MTU and its fascicles. In addition, three-dimensional kinematics and kinetics of the lower limb, as well as US images of VL fascicles were collected during submaximal cycling at cadences of 40, 60, 80 and 100 RPM. Ultrasound measures revealed a significant increase in fascicle shortening as cadence decreased (84% increase across all conditions, p < 0.01), whereas there were no significant differences in MTU lengths across any of the cycling conditions (maximum of 6%). The MTU analysis resulted in greater predicted force capacity across all conditions relative to the force-velocity relationship (p < 0.01). These results reinforce the need to determine muscle mechanics in terms of separate contractile element and connective tissue length changes during isokinetic contractions as well as dynamic movements like cycling.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
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Created: Wed, 10 Jan 2018, 09:42:20 EST by Julia Finnane on behalf of School of Human Movement and Nutrition Sciences