Sorting through the scientific studies on the clinical response to static magnetic therapy in various conditions is as much a quagmire now as it was when we first did this topic 11 years ago. A major problem with the human trials is that many authors don't give enough technical details to make it possible to compare different studies.
Even if the disease being studied is the same, such as arthritis, but one study is negative and another positive?and they don't include details such as the stage of arthritis, type of magnet, strength of magnetic field, distance from the skin and duration of exposure to the field?they can't be compared. Human studies also tend to rely heavily on subjective results like patient questionnaires.
Animals are easier. Their environment and level of exercise can be carefully controlled. it's even possible to use animals that are all of the same strain, reducing or eliminating factors like weight and pain tolerance. Using animals also forces researchers to use tangible measurements rather than questionnaires and animals are not subject to the ?placebo effect? because they don't know they're being treated.
One such study in Japan used rats of the same strain, all on the same diet and living conditions. Sixty rats were used; 20 as normal controls, 40 with arthritis induced in a hind foot. Of the 40 arthritic rats, half were treated by exposure to a static magnetic field and half not exposed.
The treated rats moved around significantly more than the untreated rats, suggesting reduced pain. Because of this, they had an increased metabolic rate. Tail-surface temperature was normal in treated rats and lower than normal in untreated. Part of this is likely a result of moving around more. Whether the magnetic exposure also increases circulation is still a point of debate.
Bone-mineral density of the untreated arthritic rats was lower than normal, but the treated rats had normal bone-mineral density. This was probably from the improved level of exercise, but in another study it was also shown a magnet implanted into bone could improve bone mineral density.
The effects of static magnet fields on circulation is still a point of hot debate. Baroreceptors are nervous-system structures that ?read? the pressure within blood vessels. A well-studied baroreceptor is located in the neck, around a portion of the carotid artery, called the carotid sinus.
Using sophisticated equipment for measuring blood flow in the microcirculation (capillaries) of the ear, a study in rabbits was able to demonstrate a significant increase in microcirculation in the ear in response to exposure to a static magnetic field exposure of the carotid baroreceptor. It was not simply an effect of the weight of the magnet on the skin over the baroreceptor because rabbits treated with sham magnets showed no response.
Their conclusion was that exposure to magnetic fields may lower blood pressure by stimulating baroreceptors, which causes the peripheral circulation to dilate. However, the field strength used was very different from what is usually found in therapeutic magnetic products. There are also studies that show long-term exposure to similar field strengths actually ends up decreasing circulation by interfering with the growth of new blood vessels.
A human study used commercially available magnetic wrap products on the forearms of healthy human volunteers for a 30-minute exposure time and measured circulation using the same techniques as in the rabbit study above. They found no difference between real magnets and sham magnet wraps. To make things even more confusing, yet another study, this time in rats, found an effect in injured skin but not normal skin.
You?ve probably seen many claims that static magnetic wraps can heal injuries. However, static magnetic exposure doesn't penetrate much below the upper levels of the skin, so these claims are unlikely, and tHere's no research to support them. However, there is research showing a highly significant decrease in the time it took skin wounds to heal when a weak static magnet was placed directly over the dressing on the wound. A virtually identical study using a stronger field (similar to those commonly found in therapy products), found no effect.
So results are mixed, complicated by different magnet strengths and duration of exposure. The bulk of the evidence to date seems to point to pain-relieving effects of moderate- to-high-strength static magnetic fields, and stimulation of wound healing with low-field strength static magnetic fields. See Magnetic Therapy charts.
OUR TRIALS. Most of the horses in our trial were athletically active and between the ages of 3 and 8, with problems of:
- ?Acute fetlock inflammation
- ?Chronic arthritis, fetlock or pastern (ringbone)
- ?Back strain (lumbosacral, in driving horses)
- ?Sesamoiditis/suspensory problems, acute and chronic
- ?Chronic sacroiliac area pain
- ?High ringbone.
No change in diet, supplements, level of exercise was allowed except in the case of acute conditions where horses were stall rested. No drugs or herbal anti-inflammatories were used.
When horses had a problem in both legs, response to products was done side by side; i.e. different products used on right and left leg. We also compared response to static magnet products with wrapping alone and to our gold standard, pulsed electromagnetic field (PEMF) therapy with the Respond Systems Bio Pulse or Maxi Pulse.
Our horses with lumbosacral back strain symptoms of muscular tightness, pain on pressure and a slightly ?roached?/arched back showed some relaxation of the muscle spasm and slight reduction in pain on pressure after 24 hours with the Dura-Tech Magnetic Mesh Sheet or Norfields Magnet Blanket on. However, it would return within less than an hour when the blanket was removed. There was no further improvement with time and ongoing treatment (2 weeks).
PEMF treatment takes 1 to 3 treatments to cut pain and spasm by about 50%. They do not return between treatments. Symptoms are completely resolved in 7 to 14 days. See PEMF Therapy.
Our horse with sacroiliac pain had recovered from an injury a year earlier but still developed stiffness and stride shortening if worked hard at the trot in harness. The static magnetic blankets had no effect. The PEMF alleviated the lameness in 3 days with twice-daily treatment. Treatment with a high frequency before exercise and a low frequency after kept him pain-free.
Static magnets of the field strengths typically used should not be applied for the first 3 to 7 days after an acute injury or flare up because of the potential to worsen inflammation. We observed this in our last magnets trial and did not repeat it in this one. Even chronic conditions can have a component of inflammation. For this reason, always build up exposure times gradually, starting with 2 hours.
BOTTOM LINE. We didn't see any obvious flare-ups of edema or heat when using any of the magnets in our trial. Each brand performed effectively and similarly. If you're using magnets alone, your choice here can be made by style or price.
However, we did see a superior response in our trial to the combination of Sore No-More and the Equine Magnetic Therapy products, suggesting that a combination of Sore No-More?s anti-inflammatory effects and magnetic exposure has additive effects.
While you may achieve the same effect with another magnet brand and Sore No-More, Equine Magnetic Therapy is the one that recommended it. Since we use all products in our trials according to the manufacturer?s instructions, this nudged Equine Magnetic Therapy into our top-choice position.
Note: Sore No-More is a cooling liniment, while other liniments may contain counterirritants and should not be used under magnets. For more information on liniments, see our January 2009 issue.
Article originally appeared in our February 2011 issue.