Blood flow restriction therapy (BFRT) is an innovative training method for the development of muscle strength and hypertrophy in the athletic and clinical settings. Through the combination of venous occlusion and low-load resistance training, it induces muscle development through a number of proposed mechanisms including anaerobic metabolism, cellular swelling, and induction of type 2 muscle fibers. Muscle weakness and atrophy are prevalent among musculoskeletal rehabilitation patients, causing delayed return to functional activity. In traditional resistance training, muscle development requires exercise loads of 70% of one-repetition maximum (1RM), but the stress placed on connective tissues and joints can be detrimental to the elderly and rehabilitation patients. However, BFRT with loads of 20% to 40% of 1RM has been shown consistently in the literature to increase muscle strength, hypertrophy, and angiogenesis. The rate of adverse effects has not been found to be greater than that in traditional high-load resistance training, but its effects on the cardiovascular system have yet to be evaluated in long-term studies. Although further investigations are needed to determine the exact mechanism and optimal usage, current evidence is promising for the application of BFRT in athletes, rehabilitation patients, and the elderly patients.