How Effective is Magnet Therapy for Muscle Pain?
Magnetism can refer to the alteration of gravitational pull to the North Pole as well as to the invisible attraction two people feel toward one another. Both definitions, however, indicate a hidden but palpable force that pulls one object to another.
Historically, magnetism was discussed as early as 625 bc. in the writings of Aristotle.1 Later, mariners learned that magnetic rocks known as lodestones acted dependably as compasses when suspended from a string. With unfailing accuracy, the stone would come to rest in a north-south line, thus indicating the direction of the ship.2
All magnets have positively and negatively charged poles. Magnets bond when opposing poles are placed next to each other and repel when like poles face each other.
The medical uses of magnets are still being explored. More than $1 billion worth of OTC therapeutic magnets have been sold worldwide to date.3
The gauss (G) is the unit of measurement of a magnetic field. The earth's magnetic field on its surface is approximately 0.5 G. Commercially available magnets usually claim strengths of anywhere from 300 G to 5,000 G; an electromagnet used in an MRI machine is 15,000 G or higher.
Basic research shows that when a magnet is placed on the skin, capillary walls relax, allowing for increased blood flow and oxygenation and removal of accumulated pain-producing prostaglandins. Theoretically, these actions relieve muscle spasms and, subsequently, pain.4
Since pain transmission requires the electrical activity found in nerve and muscle cells, properly aligned magnets could either block that action or, in cases of injury, promote healing.5 Magnets can be used in a constant, uninterrupted application (static therapy) or with manipulation of the magnetic field (pulsed therapy).
A meta-analysis of published clinical trials testing the efficacy of magnet therapy for pain showed no clear, statistically significant differences.6 Of the 29 studies examined, nine were randomized, placebo-controlled trials that explored the use of magnets for musculoskeletal pain. Four of these trials demonstrated a measurable reduction in pain but were not consistent in the strength of magnet used, length of use, and positioning of the magnets.
Of the four studies showing positive results, one was a small trial examining the effect of magnet therapy on fibromyalgia pain.7 This trial utilized a magnetic mattress pad of 1,100 G. Participants were randomized either to a placebo pad or the magnetic pad, and slept on the same pad for 16 weeks.
The patients were assessed for pain, fatigue, myalgia, physical function and sleep quality using the Fibromyalgia Impact Questionnaire. The magnetic pad group had statistically significant improvement in all areas compared with little or no change in the placebo group.
A small clinical trial used pulsed electromagnetic therapy (PEMT) to treat chronic low back pain.8 A total of 36 patients were randomized to PEMT or placebo treatment performed three times a week for three weeks. Patients were then followed for four weeks and asked to rate their pain on a numerical scale. Individuals in the treatment group reported a statistically significant decrease in pain for the entire month.
Another unique trial evaluated the efficacy of magnet therapy for menstrual pelvic pain.9 A device in the underwear secured the magnets to assure contact with the pelvis.
In this trial, 35 women with documented dysmenorrhea were randomized to wear either a strong magnet garment or a weaker magnetic placebo device for the two days prior to menses until the end of their cycle. Blinded results assessed by the McGill Pain Questionnaire showed a statistically significant reduction in pain in the group wearing the strong-magnet garment.