Objectives: The aim was to determine metabolic and hormonal responses to strength training with or without superimposed electromyostimulation (EMS) at the beginning and the end of a 6 week training period.
Methods: 20 strength trained subjects were randomly assigned to two groups. The first group (S) performed 4 sets of back squats with a constantly adjusted additional load of their individual 10 repetition maximum (10 RM) twice a week over 6 weeks. The second group (S+E) did the same training program with superimposed EMS on leg and trunk muscles. Physiological responses were determined before and after the first (TS 1) and the last training session (TS 12).
Results: No significant differences of hormonal responses could be observed between groups and TSs. However, small to large effects on metabolism occurred between groups and TSs. Delayed onset muscle soreness (DOMS) was significantly higher 48h after TS 1 for S+E.
Conclusions: Despite a higher DOMS after S+E, there is no acute effect of superimposed EMS on hormonal response to exhaustive resistance exercise. We suggest that, because of the high resistance during 10 RM bouts, most of the muscle fibers are already activated and superimposed EMS only activates few additional muscle fibers.