Skeletal muscle has the remarkable ability to remodel and repair when exposed to various stimuli such as exercise training and injury. Many factors contribute to the maintenance of healthy muscle mass throughout the lifespan including a functional population of resident muscle stem cells, commonly referred to as satellite cells (SC). When SC become active in response to a stimulus they proliferate and differentiate, eventually fusing to existing myofibres or to each other giving rise to new myotubes; while some SC revert to quiescence to maintain the SC pool. This process is termed 'the myogenic programme' and is governed by a complex network of transcription factors termed myogenic regulatory factors. SC are absolutely necessary for the repair of skeletal muscle, however, their role in mediating skeletal muscle remodelling following exercise training remains debatable. The effect of resistance exercise on SC content has been extensively studied in humans. However, a paucity of information exists in regards to the effect of 'non-resistance' type exercise training on SC content and function in healthy young adults. The purpose of this thesis was to determine the impact of nonhypertrophic exercise training on SC content. We examined the effect of high intensity interval training on the SC pool and determined that there was an increase in SC associated with remodelling hybrid fibres. We extended upon these findings by demonstrating that several high intensity interval training paradigms and traditional endurance training all resulted in an increase in SC pool activity without an overall expansion of the SC pool. Skeletal muscle regeneration is impaired in old rodents and is associated with a reduction in SC content. We therefore sought to determine whether nonhypertrophic exercise training in old mice was able to improve the regenerative response following injury. Exercise training resulted in an increase in SC content and improved skeletal muscle regeneration in old mice. In addition to previous work implicating SC in mediating skeletal muscle hypertrophy induced by resistance exercise training, this thesis provides evidence that SC are able to respond to exercise stimuli that are nonhypertrophic in nature. In addition, we demonstrate that nonhypertrophic exercise training results in an increase in SC content in old mice and this likely contributed to the improvement in skeletal muscle regeneration observed in old mice pre-conditioned with regular exercise. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/18943 |
| Date | January 2016 |
| Creators | Joanisse, Sophie |
| Contributors | Parise, Gianni, Kinesiology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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