On page 30 of the book states that any energy stored in the form of fat and carbohydrates must be converted into ATP. What about protein? I hear about muscle breakdown isn’t muscle made of protein?
Phillip, good afternoon I hope you are well and having a great Thursday. With regard to your question, consider the following as it pertains to protein as a substrate for exercise. Later in the module we elaborate on the use of protein as well. Our bodies are amazing and one of the amazing organs in our body is our liver responsible for over 600 enzymatic reactions. For exercise sessions lasting longer than 90 minutes the body can turn to amino acids for up to 18% of its energy needs. Without sufficient energy, our body has the ability to break down muscle tissue for use as an energy source during heavy exercise. This process is known as gluconeogenesis, which is the production of glucose from nom carbohydrate sources. The part of the reaction that pertains to our discussion is known as the glucose – alanine cycle. During this cycle the BCAAs (leucine, isoleucine, and valine) are stripped from the muscle tissue and parts of them are converted to the amino acid metabolite of alanine, which is transported to the liver and converted to glucose. Branched- chained amino acids are metabolized directly in the muscle and can be converted into energy to prevent muscle catabolism.
We hope this helps. Take care and have a great day.
