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.
Slow-twitch muscle fibers are slower to contract, but they take a long time to fatigue. This makes them ideal for endurance work. In fact, they play a role in many of our activities of daily living, such as walking, housecleaning and maintenance of your posture.