Impact of extremely low-frequency magnetic fields on human postural control

Studies have found that extremely low-frequency (ELF, < 300 Hz) magnetic fields (MF) can modulate standing balance; however, the acute balance effects of high flux densities in this frequency range have not been systematically investigated yet. This study explores acute human standing balance responses of 22 participants exposed to magnetic induction at 50 and 100 mTrms (MF), and to 1.5 mA alternating currents (AC). The center of pressure displacement (COP) was collected and analyzed to investigate postural modulation. The path length, the area, the velocity, the power spectrum in low (< 0.5 Hz) and medium (0.5-2 Hz) bands have computed and showed the expected effect of the positive control direct current (DC) electric stimulation but failed to show any significant effect of the time-varying stimulations (AC and MF). However, we showed a significant biased stabilization effect on postural data from the custom experimental apparatus employed in this work, which might have neutralized the hypothesized results.