<p> The work in this thesis describes the metabolic and structural response of human skeletal muscle to acute exercise and nutritional manipulation. Over a series of three studies, healthy young men performed acute bouts of either endurance or resistance exercise, and a range of invasive and non-invasive techniques were applied to examine the muscle adaptive response during exercise and recovery. Study 1 investigated the hypothesis that co-ingestion of protein with carbohydrate during exercise would improve oxidative energy metabolism and attenuate ultrastructural disruption during prolonged 90 min of cycling at ~70% VO2peak. While protein ingestion increased blood amino acids, there was no difference between treatments in glycogen degradation or the content of TCA cycle intermediates during exercise, or the blood concentration of plasma creatine kinase (CK) after 24 h of recovery. Given the limitations associated with traditional indirect markers of muscle injury, study 2 examined the potential for a non-invasive imaging technique, diffusion tensor magnetic resonance imaging (DT-MRI), to detect exercise-induced changes in skeletal muscle structure. Subjects performed 300 eccentric actions of the leg extensors, a protocol previously shown to induce histological evidence of muscle disruption. DT-MRI revealed changes consistent with muscle disorganization 24 h post-exercise compared to baseline, including decreased fractional anisotropy (FA) and increased tensor eigenvalue λ3. The exercise protocol also induced changes in traditional direct and indirect markers of muscle injury, including Z-band streaming, increased blood CK and a decrease in force-generating capacity. Study 3 examined the potential for DT-MRI to detect structural changes in response to an acute bout of work, previously shown to induce muscle damage that more closely simulated normal endurance exercise. Subjects performed 45 min of downhill running (-10° grade) and DT-MRI revealed increased ADC and tensor eigenvalue λ3 24 h post-exercise compared to baseline, in addition to increased plasma CK and decreased force-generating capacity. The main finding from the thesis is the application of DT-MRI to non-invasively detect exercise-induced changes in skeletal muscle structure as verified using well understood direct and indirect measures of muscle damage.</p> / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/18992 |
| Date | 09 1900 |
| Creators | Cermak, Naomi M. |
| Contributors | Gibala, Martin J., Kinesiology |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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