Histochemical identification of skeletal muscle fiber type-skeletal muscle in normal men and rats.

By applying a histochemical method to demonstrate the myosin ATPase activity of the skeletal muscle of humans and rats after preincubation in acidic and alkaline media, the muscle fiber types could be identified. The human skeletal muscle fibers can be classified into 4 types (I, IIa, IIb and IIc). The rat skeletal muscle fibers can be distinguished into 5 types (Ia, Ib, IIa, IIb and IIc). By using 12 kinds of histological and histochemical staining methods, we studied the activities of several enzyems and their staining patterns in the various types of muscle fibers, and then calculated the percentage of each fiber type in humans.