Nutritional impact on molecular and physiological adaptations to exercise : nutrition matters

Skeletal muscle responds to exercise by a diversity of processes that collectively contribute to short-term and structural adaptations to the demanded performance capacities. There is common consensus that, in general, adequate nutrient availability during and after exercise is important to maximise skeletal muscle adaptation and ultimately performance. At the same time, several knowledge gaps remain regarding the precise mechanisms underlying these effects on adaptation, the most optimal nutrient composition in relation to type of exercise, optimal timing etc. This dissertation addresses some of these unsolved issues by studying the role of carbohydrates and proteins during adaptation following different forms of exercise. The first part (chapters 2 – 4) focusses on carbohydrate availability with resistance exercise, whereas the second part (chapters 5 - 7) specifically addresses the effects and potential of protein supplementation with endurance training. In chapter 2 we reviewed the existing literature regarding the role of skeletal muscle glycogen with endurance and resistance exercise. Based on this review we concluded that the role of muscle glycogen levels and/or carbohydrate availability on the skeletal muscle adaptive response to resistance exercise requires further scientific attention. To experimentally explore this, we assessed the impact of a pre-exercise meal that differed in macronutrient content on skeletal muscle glycogen levels and acute transcriptional level analysing specific mRNAs in the post-resistance exercise period in chapter 3. Specifically, after a glycogen depleting endurance exercise session in the morning, subjects received an isocaloric mixed meal containing different amounts of carbohydrates and fat 2 hours before a resistance exercise session in the afternoon, while ample protein was provided throughout the day. We hypothesized that some of the selected mRNAs associated with substrate metabolism and mitochondrial biogenesis would dif