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.
The three main types are skeletal muscle, smooth muscle, and cardiac muscle. Skeletal muscle has a striped appearance earning its other name striated muscle. It is designed to work at a moments notice but it tires easily. Smooth muscle is not striped. It is designed to work slowly so therefore it tires slowly.