PhD Oral Exam - Francis Parenteau, Health and Exercise Science

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

Dietary choices have a direct impact on the gut microbiome, which in turn influences several body functions. In recent years, polyphenols, which are plant secondary compounds, have been shown to have prebiotic-like effects and associated with multiple health benefits. Interestingly, polyphenols also have a low bioavailability, which means that most of their effects are mediated by the gut microbiota. Cranberries are native to North America and have the highest polyphenol content and antioxidant capacity among the commonly consumed fruits and vegetables. Furthermore, cranberries stand out due to their high levels of the rare A-type proanthocyanidin (PAC-1), which is believed to be the main contributor to the beneficial effects. Recently, the concept that a link between skeletal muscle and the host’s gut microbiota exists was put forward. Strong physiological evidence has been published to support the existence of this gut-muscle axis, and a few research groups have proposed that supplementation with polyphenols may promote improved muscle function, and consequently, improved exercise performance. One proposed mechanism for the positive effects of polyphenols on muscle function is through improved mitochondrial capacity. Mitochondria are the main producers of ATP in the body, and their amount and ability to generate energy as fast and efficiently as possible is directly related to performance, especially in endurance athletes. The effect of cranberry polyphenols on exercise performance and skeletal mitochondrial function has not been explored before. This dissertation consists of five chapters. Chapter 1 introduces key concepts to provide background information and states the rationale, objectives, and hypotheses of the dissertation. Chapter 2 describes a rodent study that aimed to investigate the effects of cranberry A-type proanthocyanidins combined with HIIT training on maximal running speed and skeletal muscle mitochondrial function. Chapter 3 consists of a systematic review with meta-analyses that synthesizes the current literature on the effects of polyphenol-rich berries on exercise performance, inflammation, and muscle damage. Chapter 4 is a clinical trial done with competitive/elite endurance runners that investigated the effects of a polyphenol-rich freeze-dried cranberry powder on running performance, lactate production, and skeletal muscle oxygenation. Chapter 5 is a follow-up study to the one described in Chapter 5 that aimed to explore the effects of the same cranberry powder on skeletal muscle mitochondrial capacity using near-infrared spectroscopy in healthy active adults. Finally, Chapter 6 discusses the findings from chapters 2-5 and provides general limitations and future research directions.