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).
1 Strength training induces hypertrophy (increase of muscle fiber size) of both type I and type II fibers, however it results in decreased mitochrondrial mass of skeletal muscle.  Combining endurance training with strength training is key to maximizing your muscles power and resistance to fatigue.