The physiological influence of alternating current electromagnetic field exposure on human subjects med./bio.

To investigate the acute effects of a 50 Hz magnetic field on blood flow velocity and muscle activity in the arm of healthy subjects.

For investigating blood flow velocity, six healthy, male volunteers participated in the study. After 10 minutes rest in sitting position, the subjects had to put their left arm on the exposure device for about 30 minutes. After a 5-minutes rest, the exposure or sham exposure started and the first measurement was carried out (time point 0). During the 15 minutes exposure/sham exposure, measurements were taken every 5 minutes (time points 1-4) and 5 as well as 10 minutes after exposure/sham exposure was finished (time points 5 and 6). For each time point, the velocity was measured in triplicate and mean values were calculated. Measurements were repeated 2-5 times on different days.
Muscle activity was assessed in a preliminary study with three individuals. Electromyography was performed continously for 33 minutes (or 38 minutes? contradictory information). After a 5 minutes rest, the measurement started. The arm was exposed/sham exposed for 15 minutes. "Weight loading" was made by holding a 5 kg weight for 2-3 minutes before and after the exposure/sham exposure. Measurements were repeated 2-4 times.
Remark EMF-Portal: Probably, subjects for measuring blood flow velocity and muscle activity were the same, because it is stated that different parameters were measured on different days.

• human
• partial body: forearm

Blood flow velocity: Differences in baselines were large between the individuals (Remark EMF-Portal: not sure when baseline was taken, maybe at time point 0?). Therefore, the changing rate (in percent) from the baseline was analyzed for every proband. The sham exposure led to a significant decrease in the blood flow velocity compared to the baseline, possibly due to the immobility. In contrast, the exposure led to a significant increase (peak at 15 minutes) when compared to the baseline and to the sham exposure conditions. After the exposure was finished the blood flow velicity decreased again.
Muscle activity (electromyography): No significant changes between exposure and the respective baselines were observed (Remark EMF-Portal: No data given for differences between exposure and sham exposure conditions).
The authors conclude that a 50 Hz magnetic field could enhance the blood circulation and hypothezise that electrical eddy currents could lead to this enhancement.