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.
Muscle Fiber Types. Skeletal muscle fibers have metabolic and mechanical differences that allow them to be classified into different types. A motor unit, which consists of a somatic efferent neuron and all the muscle fibers it innervates, is comprised of muscle fibers that are all of the same type.hus the classification for muscle fibers also applies for motor units. Some of the different characteristics of muscle fiber (and motor unit) types are listed in the table. These are grouped in colors according to four basic features about muscle fibers.