reduce swelling, relax muscles, stimulate blood-flow= heal faster. also, they work better at reducing inflammation than Ibuprofen does, so I don't have to destroy my liver and stomach lining to try and reduce my inflammation. you need to get rid of all your swelling/inflammation as fast as possible to have 100% circulation. The more red blood cells you get flowing past your injury, the faster you heal. Ultrasound therapy does just that. 50$ per session at physiotherapy sucks, especially when I could have my own ultrasound machine-- which is essentially all they do at physio that I couldn't (before) do at home anyway. I just dont want to drop 200$+ on a ultrasound machine that doesn't work, so  I'd like to know if anyone know anything about these machines before I buy. I can't find any consumer reviews either. BTW, i tore my acl= mega lame