An essential nutritional aspect for building and repairing muscle after exercise is protein. Consuming adequate protein helps to repair micro-tears in muscle fibers caused during workouts, facilitating growth and recovery. Recommended sources include lean meats, fish, dairy products, legumes, and plant-based proteins like quinoa and tofu. It is crucial to consume protein following exercise, ideally within the anabolic window, which is around 30 to 60 minutes post-workout, to maximize recovery and muscle synthesis.