What conditions are needed to maintain performance and muscle growth?

What conditions are needed to maintain performance and muscle growth? How does the process of nutrition, respiration and removal of decay products occur?

For performance and muscle growth, you need to get enough protein and carbohydrates. Lipids are also needed, but in small amounts. The process of respiration, nutrition and removal of decay products can occur at the cellular level, as well as at the organismal level. We have the organs of respiration, nutrition and excretion to support all these processes. They are regulated by the brain as well as certain hormones and enzymes. For example – digestion is possible thanks to digestive enzymes that are secreted by the stomach, pancreas and intestinal bacteria.