The function of protein in muscle building is crucial, as it provides the essential amino acids necessary for muscle repair and growth. After exercise, protein consumption stimulates muscle protein synthesis, allowing the body to recover and develop stronger muscle fibers. Different sources of protein, such as lean meats, dairy, and plant-based options, can aid in meeting daily protein requirements. For effective muscle building, a combination of regular strength training and an adequate protein intake is essential for optimal results in fitness and recovery.