Normal levels of creatinine in the blood are approximately 0.6 to 1.2 milligrams (mg) per deciliter (dL) in adult males and 0.5 to 1.1 milligrams per deciliter in adult females. Muscular young or middle-aged adults may have more creatinine in their blood than the norm for the general population.
Types of muscle fibers. Skeletal muscle, the type that is responsible for moving our muscles when we run, is comprised of three different muscle fiber types, each with its own advantages, disadvantages, and specialty.
Type II muscle fibers display a faster shortening velocity than type I muscle fibers. A higher proportion of type II muscle fibers may therefore be beneficial for strength and power sports. However, the extent to which type II muscle fibers are displayed may be determined by individual muscles and genetics.