Magnets, my foot!
Nathan Seppa
People in the United States spend roughly $500 million every year on wearable magnets for treating aches and pains. The devices are advertised as increasing blood flow and altering nerve signals.
A new study finds that, at least for one condition, shoe inserts containing magnets don't work any better than similar inserts without magnets. The problem examined was bottom-of-the-foot pain—a symptom of plantar fasciitis, an inflammation of the tough connective tissue that links the ball of the foot with the heel. Scientists at the Mayo Clinic in Rochester, Minn., report the findings in the Sept. 17 Journal of the American Medical Association.
The researchers recruited 101 people with sharp foot pain and gave 57 of the volunteers fitted, cushioned insoles containing magnets. The other 44 volunteers got similar insoles fitted with nonmagnetized metal.
After 8 weeks, about one-third of the volunteers in both groups reported a decrease in their pain, says Mark H. Winemiller, one of the study investigators. Some of these gains could result from the insoles' cushioning, but it's difficult to rule out a placebo effect, he says.
While this study didn't address pain in other areas of the body—such as the wrists—the data suggest that people marketing magnets for pain relief may have a tougher sell from now on, he says.
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Letters:
This article makes no mention of the type of magnetic insoles used—multipolar phased array or bipolar—nor the strength. I suffer from peripheral neuropathy, and a set of multipolar-phased-array-type magnetic insoles has been the only effective treatment.
James White
Hillsboro, OR
The researchers used insoles containing a magnet with a bipolar multiple circular array, with a surface magnetization of 192 gauss.—N. Seppa
References:
Winemiller, M.H., et al. 2003. Effect of magnetic vs. sham-magnetic insoles on plantar heel pain. Journal of the American Medical Association 290(Sept. 17):1474–1478. Abstract available at http://dx.doi.org/10.1001/jama.290.11.1474
Further Readings:
Christensen, D. 2001. Medicinal mimicry. Science News 159(Feb. 3):74–78. Available at http://www.sciencenews.org/articles/20010203/bob9.asp.
______. 2001. Placebos are dead, long live placebos. Science News 160(Sept. 15):175. Available to subscribers at http://www.sciencenews.org/articles/20010915/note16.asp.
Collacott, E.A., et al. 2000. Bipolar permanent magnets for the treatment of chronic low back pain. Journal of the American Medical Association 283(March 8):1322–1325. Abstract available at http://dx.doi.org/10.1001/jama.283.10.1322.
Sources:
Mark H. Winemiller
Department of Physical Medicine and Rehabilitation
Mayo Clinic
200 First Street, SW
Rochester, MN 55905
From Science News, Volume 164, No. 16, October 18, 2003, p. 254.
