Amino acids can provide from a few to about 10% of the total energy during exercise. However, the effect of endurance exercise on muscle protein metabolism is still relatively well studied. What are the consequences of using amino acids as an energy source? Can we avoid the negative consequences?
Protein degradation in skeletal muscles during exhaustive endurance exercise
Questions to be addressed in this project include whether carbohydrate intake can reduce protein degradation and whether protein degradation is associated with reduced performance.
Carbohydrate and fat are the most important energy substrates during endurance exercise. The proportions of utilization of these nutrients as energy substrates, depending on the intensity of exercise, have been extensively studied. However, depending on training duration and intensity, amino acids can provide from a few to about 10% of the total energy during exercise. The effect of endurance exercise on muscle protein metabolism remains relatively understudied. This may be related to the general observation that such exercise does not usually result in significant gains in muscle size. However, changes in muscle protein synthesis after endurance exercise are relevant for tissue repair and remodeling, as well as changes in the synthesis of protein fractions that do not contribute to muscle hypertrophy such as the mitochondrial proteins.
In this project, trained cyclist will cycle to exhaustion in a double-blinded, balanced, crossover way while ingesting either a carbohydrate drink or a placebo. Performance as well as markers of protein degradation in skeletal muscles will be measured. Biological fluids will be collected, and their values will be compared with the physiological values measured in the participants in order to be able to establish a quantitative overview of the use of energy substrates during exercise.