The purpose of this thesis was to investigate the effects of nutritional supplementation following resistance exercise on protein metabolism, muscle glycogen resynthesis rate, hormonal responses and training status through two unique investigations. The purpose of the first investigation was to determine the effect of post-resistance exercise glucose supplementation upon skeletal muscle fractional synthetic rate (FSR), urinary urea excretion, and whole body and myofibrillar protein degradation (WBPD and MPD, respectively). Eight healthy young males performed unilateral knee extensor resistance exercise(8sets/~1 0reps/~85% 1 RM) such that the non-exercised limb served as a control. They received a carbohydrate (CHO) supplement (1g/kg) or placebo (PL) immediately (t=Oh) and 1 h (t=+1 h) following exercise. FSR was determined for both exercised (EX) and control (CON) limbs by incremental L-[1-13C]leucine enrichment of biopsy samples of vastus lateralis over -10 hours post-exercise. Plasma insulin and glucose were determined at t= -1.5, 0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, -10, and -10.5h post-exercise. MPD and WBPD were estimated from 24 hr urinary 3-methylhistidine (3-MH) and L-[1-13C]leucine flux, respectively, and whole body net protein balance was estimated from 24 hr urinary urea excretion. Plasma insulin concentration was greater (p<0.01) at 0.5, 0.75, 1.25, 1.5, 1.75 and 2 h in the CHO compared to PL condition, as was plasma glucose at 0.5 and 0. 75 h (p<0.05). FSR was 36.1% greater in the CHO/EX leg than in the CHO/CON leg (p=N.S.) and 6.3% greater in the PUEX leg than in the PUCON leg(p=N.S.). 3-MH excretion was lower in the CHO (110.43 ± 3.62 J μmol/g creatinine) than PL condition (120.14 ± 5.82)(p<0.05) as was urinary urea nitrogen(8.60 ± 0.66 g/g creat vs. 12.28 ± 1.84)(p<0.05). These findings suggest that CHO supplementation (1g/kg) immediately and 1h following resistance exercise can significantly decrease myofibrillar protein breakdown and urinary urea excretion, thus resulting in a more positive muscle and whole body protein balance. The purpose of the second investigation was to determine the effect of various nutritional supplements upon whole body protein synthesis, urinary urea excretion, and whole body and myofibrillar protein degradation (WBPD and MPD respectively). Ten healthy young male resistance athletes performed a whole body circuit set workout (9 exercises/3 sets/80% 1 Repitition Maximum). Exercises for the legs were performed unilaterally so that the non-exercised leg served as a control They received a carbohydrate (CHO) supplement (1g/kg), a mixed CHO/PRO/FAT supplement (isoenergetic to CHO supplement)(68% CHO, 22% PRO, 10% FAT) or placebo (PL) immediately (t=Oh) and 1 h (t=+1h) following exercise. Immediately following exercise muscle glycogen was significantly lower (p<0.05) in vastus lateralis of the exercised leg than in the control leg immediately post-exercise in all three conditions. Both the CHO and CHO/PRO/FAT supplements resulted in significantly greater increases (p<0.05) in plasma insulin and glucose post-exercise than PL. The CHO and CHO/PRO/FAT also resulted in significantly greater(p<0.05) rates of muscle glycogen resynthesis vs. Placebo. No significant differences were observed between the three conditions for plasma testosterone and cortisol concentration post-exercise. Similarly, no differences were observed between the three conditions for urinary creatinine, and 3-MH and urea nitrogen excretion. Thus, nutritional supplements do not appear to decrease myofibrillar protein degradation as indicated by 3-MH and urea nitrogen excretion in highly trained resistance athletes. Taken together, the two studies suggest that highly trained resistance athletes and untrained individuals both benefit from nutritional supplementation following resistance exercise, but may do so through different mechanisms. / Thesis / Master of Science (MS)

PhD Thesis / Metabolomics offers a systemic approach to discover clinical biomarkers for early detection of chronic diseases while also revealing underlying mechanisms relevant to human disorders of complex aetiology. Metabolomic studies in support of chronic disease prevention have focused primarily on surrogate biofluids (e.g., serum, plasma) for analysis due to their routine and less invasive sample collection in a clinical setting. However, biofluids are non-organ specific and thus are reflective of confounding biochemical processes within the body that are often difficult to interpret. As a result, it is necessary to assess metabolite changes localized within tissues since they are the direct site of pathogenic processes, in order to obtain more robust and specific biomarkers. This thesis aims to contribute to new advances in biomarker discovery and tissue metabolomic studies using multiplexed separations together with innovative data workflows based on multisegment injection-capillary electrophoresis-mass spectrometry (MSI-CE-MS). Chapter II introduces a high throughput yet targeted screening method for accurate quantification of serum γ‐glutamyl dipeptides from a cohort of overweight Japanese non-alcoholic steatohepatitis (NASH) patients that may allow for better risk assessment of long-term survivorship complementary to histopathology. Chapter III introduces a non-targeted metabolite profiling strategy for fasting plasma samples from prediabetic, older adults undergoing short-term step reduction (<1000 steps/day) in order to identify adaptive metabolic responses to abrupt changes in physical inactivity for early detection of sarcopenia in high-risk older persons. Chapter IV describes the first metabolomics study to characterize the human skeletal muscle metabolome from mass-restricted tissue biopsies together with matching plasma samples, which identified novel metabolic signatures associated with strenuous interval exercise, as well as treatment effects from high-dose bicarbonate pretreatment that delays the onset of muscle fatigue. Lastly, in Chapter V, metabolite coverage was expanded to include fatty acids for comprehensive characterization of murine placental tissue metabolome, which revealed sex-specific metabolic adaptations during gestation from maternal dams fed a standardized diet. In summary, this thesis contributes to new innovations in metabolomics for the discovery of novel biomarkers from blood and/or tissue specimens as required for early detection of chronic diseases relevant to population health, which were also used to validate the efficacy of therapeutic interventions based on physical activity to support healthy ageing. / Thesis / Doctor of Philosophy (PhD)