Testolone (RAD‑140) is an orally active, non-steroidal Selective Androgen Receptor Modulator (SARM) that binds selectively to androgen receptors (AR) in skeletal muscle and bone tissue. By mimicking the action of endogenous testosterone, RAD‑140 activates anabolic signaling pathways that promote protein synthesis, muscle hypertrophy, and increased strength, while exhibiting minimal androgenic effects in non-target tissues such as the prostate and liver. RAD‑140 has been shown to support bone density, enhance recovery from muscle stress or injury, and improve overall body composition by favoring lean mass accumulation over fat gain. Its selective receptor binding allows for potent anabolic activity without the systemic side effects commonly associated with traditional anabolic steroids. Mechanistically, RAD‑140 modulates transcriptional activity in target cells, influencing gene expression related to growth, repair, and metabolic regulation. This results in improved muscular endurance, enhanced tissue repair, and potential neuroprotective effects, as some studies suggest RAD‑140 may interact with androgen receptors in the central nervous system.