Abstract
Electrical muscle stimulation (EMS) has been shown to stimulate the production of myokines (i.e., brain-derived neurotrophic factor (BDNF)), but the most effective EMS parameters for myokine production have not been fully elucidated. The purpose of this study was to quantify the optimal EMS frequency for stimulating myokine production. This study included sixteen young adults (male, n = 13, age = 27.3 ± 5.5 years). Participants underwent four EMS interventions (20 min each) with the following conditions: (1) 4 Hz, (2) 20 Hz, (3) 80 Hz, and (4) control (no intervention). Blood samples were obtained before and immediately after EMS. For the control condition, blood samples were taken before and after 20 min of quiet sitting. BDNF and cathepsin-B levels were analyzed in serum. Compared to preintervention levels, stimulation at 20 Hz resulted in significantly greater postintervention cathepsin-B and BDNF levels (p < 0.01). On the other hand, the control condition did not result in a significant change between pre- and posttreatment. Furthermore, stimulation at 20 Hz caused significantly larger increases in cathepsin-B and BDNF levels than stimulation at 4-80 Hz or the control condition (p < 0.05). In conclusion, stimulation at 20 Hz effectively causes a robust cathepsin-B and BDNF response. Based on these results, we suggest a new strategy for rehabilitation of people with neurological disorders.