Occlusion or tourniquet training involves exercising with restricted blood flow to the working muscles. Decreasing muscle blood flow may trigger cell damage, inflammation, cell stress and anabolic hormone release. Muscles grow in response to physical and chemical stress, so it seems reasonable that restricting blood flow to muscles during training might promote hypertrophy. A University of Tokyo study compared the effects of low-resistance blood flow restricted training with high-resistance weight training. Both treatments caused increases in strength, but muscle cross-sectional area in affected muscles increased more from traditional weight training. While occlusion training might have clinical applications in physical therapy and space travel, it does not produce the benefits of traditional weight training.
Source: (Clinical Physiology and Functional Imaging, 31: 347-351)