Skeletal muscle performs essential functions, including movement and posture. Musculoskeletal disorders can disrupt these functions, leading to temporary or permanent impairment. As most muscle abnormalities will cause morphological and physiological changes in skeletal muscle, identifying diseased or injured skeletal muscle relies on having a frame of reference, i.e. a correct characterization of what is considered healthy or 'normal' skeletal muscle.
Non-invasive Magnetic Resonance Imaging (MRI) techniques such as 1H Magnetic Resonance Spectroscopy (1H-MRS) to assess the biochemical environment, Magnetization Transfer (MT) to study water dynamics and Blood Oxygen Level Dependent (BOLD) signal to study blood flow and relative (de)oxy-Hb concentration have yet to be extensively explored in skeletal muscle. Therefore, to improve the knowledge of the biochemical environment of skeletal muscle, a series of experiments were performed using these techniques in calf muscles.
1H-MRS investigations showed high repeatability of metabolite quantification within and across scanning sessions despite its challenges due to the high structural organization of skeletal muscle. Furthermore, differences in the metabolic profile between endurance vs. power-oriented participants at rest were found, suggesting 1H-MRS could be used as a non-invasive technique to assess muscle fiber composition.
A multimodal MT, and BOLD study were performed on exercised skeletal muscle to complement the metabolic understanding of skeletal muscle. It was shown that high-quality data could be obtained in simultaneous studies of BOLD/EMG. In addition, during a multimodal MT and BOLD acquisition, MT signal showed a decrease after exercise and was linearly correlated to the BOLD signal activation. The ability of MT to distinguish between highly/lowly activated muscle groups during exercise opens the opportunity to non-invasively investigate muscle group recruitment with a higher spatial resolution compared to EMG, and lower scanning times compared to BOLD.
Overall, the main purpose of this thesis was to investigate, characterize and provide unique metrics to study the functional and metabolic profile of healthy skeletal muscle at rest and during exercise. / Thesis / Master of Applied Science (MASc) / Skeletal muscle performs vital functions such as movement, heat generation, and posture. The impact of musculoskeletal disorders, which can disrupt these functions and cause temporary or permanent impairment of physical activity and movement, is expected to grow in the future. Correctly characterizing healthy or 'normal' skeletal muscle is necessary to identify diseased or injured skeletal muscle, as most muscle abnormalities cause changes in morphology and physiology. Non-invasive MRI techniques to assess the biochemical environment, water dynamics, blood flow and relative (de)oxy-Hb concentration have yet to be extensively explored in healthy skeletal muscle. Thus, the primary purpose of this thesis was to investigate, characterize and provide unique metrics to study the functional and metabolic profile of healthy skeletal muscle at rest and during exercise. The metrics investigated can be used to establish a baseline to detect abnormal skeletal muscle.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/28502 |
| Date | January 2023 |
| Creators | Amador-Tejada, Alejandro Ian |
| Contributors | Noseworthy, Michael, Biomedical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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