Simply put, the brain stimulates nerves that control individual muscle fibers to contract. (philmaffetone.com)
However, height is not as precise an indicator of individual muscle tissue as lean mass. (sciencedaily.com)
He also provides the methods you needs to correctly increase the intensity of your workouts and shows you how to split train with bodyweight exercises so that you can work individual muscle groups. (unique-bodyweight-exercises.com)