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.
Training To Maximize Your Muscle Fiber Types! 1  If you can do only 4 to 7 reps with 80% of your 1 RM, you have mostly fast twitch fibers in that muscle. The reason you will only be able to do 4 to 7 reps with 80% of your 1 RM is that fast twitch muscle fibers are strong but don't have great endurance.