The specificity of training adaptation in skeletal muscle
Creators: name: Camera, Donny
Publisher: name: RMIT University
Year: 2024

description: It is generally accepted that skeletal muscle adaptation to repeated bouts of contractile activity are specific to the mode, intensity, and duration of the exercise stimulus, but the molecular mechanisms regulating this specificity of adaptation remain poorly defined. The interaction of nutrient and substrate availability is also critical in determining skeletal muscle adaptation and has the capacity to modulate the specificity of training response. Accordingly, the primary aims of the studies undertaken for this thesis were: 1) to determine the molecular adaptations regulating the specificity of training adaptation following resistance and endurance exercise, and 2) to demonstrate how substrate (glycogen) and nutrient (protein/carbohydrate) availability impact adaptation responses following ‘concurrent’ training. The first study (Chapter Two) determined the time course of Akt-mediated and AMPK signalling during the acute post-exercise recovery period following resistance and endurance exercise in human skeletal muscle. The second study described in Chapter Three determined the effect of muscle glycogen concentration and post-exercise nutrient ingestion on anabolic signalling and rates of myofibrillar protein synthesis after resistance exercise. The final study (Chapter Four) elucidated the effect of protein supplementation on anabolic signalling and rates of myofibrillar and mitochondrial protein synthesis after a single bout of consecutive resistance and endurance exercise. The results from the studies undertaken for this thesis provide novel information regarding the effects of exercise mode, glycogen availability, and nutrient supplementation on the molecular mechanisms involved in the specificity of training adaptation. Specifically, resistance and endurance exercise are equally capable of mediating translational signalling responses during the acute recovery period. In addition, low glycogen It is generally accepted that skeletal muscle adaptation to repeated bouts of contractile activity are specific to the mode, intensity, and duration of the exercise stimulus, but the molecular mechanisms regulating this specificity of adaptation remain poorly defined. The interaction of nutrient and substrate availability is also critical in determining skeletal muscle adaptation and has the capacity to modulate the specificity of training response. Accordingly, the primary aims of the studies undertaken for this thesis were: 1) to determine the molecular adaptations regulating the specificity of training adaptation following resistance and endurance exercise, and 2) to demonstrate how substrate (glycogen) and nutrient (protein/carbohydrate) availability impact adaptation responses following ‘concurrent’ training. The first study (Chapter Two) determined the time course of Akt-mediated and AMPK signalling during the acute post-exercise recovery period following resistance and endurance exercise in human skeletal muscle. The second study described in Chapter Three determined the effect of muscle glycogen concentration and post-exercise nutrient ingestion on anabolic signalling and rates of myofibrillar protein synthesis after resistance exercise. The final study (Chapter Four) elucidated the effect of protein supplementation on anabolic signalling and rates of myofibrillar and mitochondrial protein synthesis after a single bout of consecutive resistance and endurance exercise. The results from the studies undertaken for this thesis provide novel information regarding the effects of exercise mode, glycogen availability, and nutrient supplementation on the molecular mechanisms involved in the specificity of training adaptation. Specifically, resistance and endurance exercise are equally capable of mediating translational signalling responses during the acute recovery period. In addition, low glycogen availability does not appear to attenuate anabolic adaptations to resistance exercise but protein ingestion is integral to the stimulation of myofibrillar protein synthesis with concurrent training. The increase in myofibrillar protein synthesis with protein ingestion following consecutive resistance and endurance exercise may ameliorate potential interference of endurance exercise on muscle hypertrophy with chronic concurrent training.