Investigation of Human Muscle Variability and its Effects on Musculoskeletal Models
Open Access
- Author:
- Infantolino, Benjamin William
- Graduate Program:
- Kinesiology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- December 15, 2010
- Committee Members:
- John Henry Challis, Dissertation Advisor/Co-Advisor
John Henry Challis, Committee Chair/Co-Chair
Stephen Jacob Piazza, Committee Member
Robert Barry Eckhardt, Committee Member
Andris Freivalds, Committee Member - Keywords:
- First Dorsal Interosseous
muscle
sarcomere length
subject-specific model parameters
muscle variability
musculoskeletal model - Abstract:
- Variability in the musculoskeletal system is apparent at the human body level in terms of body height and shape. However, daily activities such as walking demonstrate stereotypical movement patterns across individuals. The literature suggests that although muscles produce stereotypical movements, at various levels of muscle variability exists. For example, whole muscles demonstrate differences in the portion of the force-length curve on which they act on. This has been demonstrated between different muscles as well as between the same muscles in different individuals. Evidence has also shown that sarcomere lengths differ along the length of muscle fibers. The First Dorsal Interosseous (FDI) muscle is the only muscle to abduct the second metacarpophalangeal joint and is therefore of interest to study its variability in light of its singular action. The purpose of the four studies in this dissertation was to investigate variability in the musculoskeletal system at various levels for the FDI muscle. Specifically, the purpose of the first study was to investigate how the output of a FDI musculoskeletal model changes with changes in model parameters. The purpose of the second study was to investigate how individual sarcomere lengths varied along single FDI muscle fibers. The purpose of the third study was to measure subject-specific FDI muscle model parameters in vivo. The purpose of the final study was to investigate, using magnetic resonance imaging, the arrangement of muscle fascicles within the FDI muscle. The studies showed that: 1. that accurate model output requires specimen-specific model parameters; 2. individual sarcomere lengths along muscle fibers exhibit long-range correlations, which has implications for determining the properties of the whole muscle from a sample of its fibers; 3. full characterization of a model of the FDI in vivo is feasible, using ultrasound imaging and a custom-made dynamometer; and 4. muscle fascicles demonstrate a complex architecture with some fascicles arranged in series. In study 1 model predicted joint moments were sensitive to the FDI model parameter set used; joint moments differed between parameter sets by up to 884.3%. In study 3 muscle model parameters were determined for three subjects, these parameters showed variability between the subjects for example the maximum velocity of fiber shortening ranged from 4.7 to 9.7 optimum fiber lengths per second. These findings demonstrate variability at multiple levels of muscle in the FDI muscle, which suggests that other muscles may also exhibit this variability which could be investigated using the methods presented in this dissertation.