Comparison of Static and Placebo Magnets on Resting Forearm Blood Flow in Young, Healthy Men

Steven C. Andrews, Gregory F. Martel, Christopher G. Roseboom

Study Design: Prospective, randomized, double-blind, placebo-controlled crossover design.

Objectives: To examine the effects of static magnets on resting forearm blood flow and vascular resistance.

Background: Despite little scientific evidence indicating benefits of wearing static magnets, recent reports have indicated a dramatic increase in the usage of magnets to treat a variety of medical conditions. Magnet manufacturers have proposed that one mechanism for pain reduction involves magnet-related blood flow alterations to the affected area.

Methods and Measures: Twenty young, healthy men (mean age ± SD = 25 ± 2 years) wore commercially available static magnets and placebos for 30 minutes on 2 separate occasions. Resting forearm blood flow was assessed in triplicate at minutes 10, 20, and 30, using venous occlusion plethysmography. Forearm vascular resistance was estimated by dividing mean arterial pressure by blood flow.

Results: The average blood flow over the 30-minute measurement period was not significantly different between the magnet and placebo sessions (mean ± SD for magnet session = 1.40 ± 0.63 ml blood × 100 ml tissue-1 × min-1; mean ± SD for placebo session = 1.36 ± 0.46 ml blood × 100 ml tissue-1 × min-1; P = 0.66). Blood flow measurements at minutes 10, 20, and 30 were also not significantly different between the magnet and placebo sessions, and forearm vascular resistance was not different between the magnet and placebo sessions at any time (P >0.05).

Conclusion: Exposure to static magnets for up to 30 minutes had the same effect on resting forearm blood flow and vascular resistance as placebo magnets. These data suggest that static magnets do not result in significant alterations in resting blood flow.

J Orthop Sports Phys Ther. 2002; 32(10):518–524.

Key Words: magnet therapy, pain management, venous occlusion plethysmography

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