Pain relief is the most common use of magnets. Magnets increase the capillary blood flow which may help flush lactic acid and other inflammatory agents that build up tissue to ease pain and inflammation. The blood supply also carries oxygen which may be helpful in relaxing muscles and relieving cramps and spasms which are oxygen starved. This is the same reason massage is often used to loosen muscles in spasm; to allow block to flow and deliver oxygen necessary to terminate the spasm.