Magnetic therapy is a pseudoscientific alternative medicine practice involving the weak static magnetic field produced by a permanent magnet which is placed on the body. It is similar to the alternative medicine practice of electromagnetic therapy, which uses a magnetic field generated by an electrically powered device. Magnet therapy products may include wristbands, jewelry, blankets, and wraps that have magnets incorporated into them. Practitioners claim that subjecting certain parts of the body to weak electric or magnetic fields has beneficial health effects. These physical and biological claims are unproven and no effects on health or healing have been established. Although hemoglobin, the blood protein that carries oxygen, is weakly diamagnetic (when oxygenated) or paramagnetic (when deoxygenated), the magnets used in magnetic therapy are many orders of magnitude too weak to have any measurable effect on blood flow. This is not to be confused with transcranial magnetic stimulation, a scientifically valid form of therapy, or with pulsed electromagnetic field therapy. Methods of application Magnet therapy involves applying the weak magnetic field of permanent magnets to the body, for purported health benefits. Different effects are assigned to different orientations of the magnet. Products include magnetic bracelets and jewelry; magnetic straps for wrists, ankles, knees, and back; shoe insoles; mattresses; magnetic blankets (blankets with magnets woven into the material); magnetic creams; magnetic supplements; plasters/patches and water that has been "magnetized". Application is usually performed by the patient. It is similar to the alternative medicine practice of electromagnetic therapy, which uses the weak electric or magnetic fields as well, but generated by electrically powered devices. Suggested mechanisms of action Perhaps the most common suggested mechanism is that magnets might improve blood flow in underlying tissues. The field surrounding magnet therapy devices is far too weak and falls off with distance far too quickly to appreciably affect hemoglobin, other blood components, muscle tissue, bones, blood vessels, or organs. A 1991 study on humans of static field strengths up to 1 T found no effect on local blood flow. Tissue oxygenation is similarly unaffected. Some practitioners claim that the magnets can restore the body's hypothetical "electromagnetic energy balance", but no such balance is medically recognized. Even in the magnetic fields used in magnetic resonance imaging, which are many times stronger, none of the claimed effects are observed. If the body were meaningfully affected by the weak magnets used in magnet therapy, MRI would be impractical. Efficacy