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.
Science Videos. Science Main Index. Muscle fibers are the cells or basic building block of the muscle. There are a few different types of muscle fiber, each designed for a specific type of muscle activity. Some muscle fibers are good for endurance exercises, other work best for the short bursts of strength exercises.