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.
Studies performed on identical twins have shown that muscle fiber composition is very much genetically determined (Komi & Karlsson, 1979), however there is evidence that both the structure and metabolic capacity of individual muscle fibers can adapt specifically to different types of training.tudies performed on identical twins have shown that muscle fiber composition is very much genetically determined (Komi & Karlsson, 1979), however there is evidence that both the structure and metabolic capacity of individual muscle fibers can adapt specifically to different types of training.