Over the last several years, the use of magnets for pain relief—based on theories that magnets improve circulation, increase blood oxygen, or decrease deposition of toxic materials in blood vessels—has increased dramatically, despite a lack of scientific evidence supporting their effectiveness. Some studies have found that magnets can relieve various sources of pain, but all have had substantial methodological limitations. Annual U.S. sales of magnetic devices are estimated to be $500 million.

Plantar fasciitis , which results from inflammation of tendons where they attach to the heel, is a common cause of foot pain among athletes and the general population. Recently, researchers conducted a randomized, double-blind, placebo-controlled trial to assess whether magnetic shoe insoles (static, or non-pulsating, magnets placed directly on the feet) provide greater improvement of plantar fasciitis pain compared with identical non-magnetized shoe insoles. The results, published in the September 17, 2003 issue Journal of the American Medical Association , indicate that magnetized insoles are no better than non-magnetized insoles in reducing plantar heel pain.

About the Study

The researchers randomly gave 101 adult men and women either shoe insoles containing an active bipolar magnetic foil (with an internal magnetization of 2,450 gauss and surface reading of 192 gauss) or sham-magnetic shoe insoles (with no magnetic properties). Participants must have had symptoms of plantat fasciitis (including tenderness and sharp, shooting pain extending from the heel across the sole of the foot) more often than not for at least 30 days.

Participants were instructed to wear the insoles for at least four hours per day, four days per week, for eight weeks. Data on pain intensity, interference with employment performance and enjoyment, and adverse effects were collected by questionnaire at baseline and at four and eight weeks.

The Findings

While a considerable proportion of each group felt all or mostly better by the end of the study (35% of the magnetic group and 33% of the non-magnetic group), no significant differences in pain intensity were found between them at baseline, four weeks, or eight weeks. Similarly, participants receiving both treatments reported that their ability to do or enjoy their work improved after the eight weeks—but the improvement in the two groups was comparable. No serious adverse effects were reported with either type of insole.

In a separate analysis, the researchers determined that participants (irrespective of group) who, at baseline felt magnets have the potential to relieve pain, reported significantly less pain at eight weeks than those not believing in the potential of magnets.

At the end of the study, neither group was better at predicting assignment than chance would dictate.

How Does This Affect You?

Many claims have been made regarding the therapeutic use of magnets. In fact, many laboratory experiments have documented the biologic effects of magnetic fields. But, according to this rigorous study, magnets imbedded within shoe insoles do not provide any more relief for plantar heel pain than do sham magnetic insoles.

Although it is not clear how the effectiveness of static magnets is related to magnetic strength, the strength of magnets used in this study is comparable with that of brands of magnetic shoes widely available at retailers. Pulsed electromagnetic fields (which induce measurable electric fields), however, are not comparable to those used in this study and therefore, no conclusions can be drawn about their effectiveness.

The bottom line is that static magnets do not appear to offer more benefit than similar objects with no magnetic field in the treatment of plantar heel pain. However, magnetic fields in general appear to be safe, and it is possible that future research will find them to be clinically effective for this or other conditions. Until then, speak with your health care provider about other, more effective treatments for plantar fasciitis.