Human satellite cells are stem cells involved in the repair and maintenance of skeletal muscle and have been proposed as the primary site of the anabolic action of AAS (
36–
37). However, the exact mechanism of action of AAS in these cells is still poorly understood. It has been proposed that AAS act through an hAR-mediated mechanism and induce the commitment of these cells into a myogenic lineage. The results of this mechanism in skeletal muscle are hypertrophy of both type I and type II muscle fibers (but not an increase in the number of fibers) (
36,
38–
43), an increase in the number of myonuclei and satellite cells resulting in an increase in the number available for conversion to skeletal muscle fibers (
38,
44–
46), and an upregulation of the number of hARs in the cells (
39,
44–
47).