Objective: To determine whether application of a commercially available static magnetic field would alter the signs and/or symptoms of delayed onset muscle soreness (DOMS) produced by exhaustive eccentric exercise.
Design: A double-blinded, randomized, and placebo-controlled study, with subjects serving as their own controls.
Setting: An outpatient physical therapy and performance center.
Participants: Twenty-three healthy volunteers (18 women; mean age, 30 y; range, 18-40 y; 5 men; mean age, 29 y; range, 19-39 y).
Intervention: After exhaustive eccentric exercise of both the right and left elbow flexor muscle groups, subjects received daily treatment with either a 350G magnet or a placebo device for 5 consecutive days.
Main outcome measures: Outcome variables, including anthropometric measurements, perceived discomfort, and muscle force production, were compared using linear mixed models.
Results: Arm circumference, relaxed elbow flexion angle, and pain increased, whereas active elbow flexion angle and maximal isometric torque decreased transiently before returning to near baseline. No significant difference in outcome variables existed between the treated and control arms. Participants reported less pain in both treated and control arms after each session, suggesting a placebo effect.
Conclusions: Static magnetic fields were no more effective than placebo in preventing DOMS.