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.
Fiber Types and Skeletal Muscle Hypertrophy The force generated by a muscle is dependent on its size and the muscle fiber type composition. Skeletal muscle fibers are classified into two major categories; slow-twitch (Type 1) and fast-twitch fibers (Type II).
Each myocyte contains many myofibrils, which are strands of proteins (actin and myosin) that can grab on to each other and pull. 1  This shortens the muscle and causes muscle contraction. 2  Therefore, slow twitch fibers are great at helping athletes run marathons and bicycle for hours.