Strange as it may sound, electromyostimulation (EMS) can strengthen muscles. EMS works by sending electrical currents to the nerves that control muscles. The electrical currents make the muscles contract. Carefully designed EMS programs can improve athletic performance.
This study looked at using EMS to increase the vertical jump of high-level Italian volleyball players. EMS was used along with plyometric jump training, a method that uses explosive movements to improve speed and power.
It worked like this. Ten volleyball players went through four weeks of the experimental training. They did three sessions each week. Each session started with a 20-minute warm-up. Then the players got EMS stimulation in specific muscles in the legs for 26 minutes. After a rest, they did five sets of ten jumps. They finished with ten minutes of stretching. They were allowed to play one practice game a week. Meanwhile, the ten players in the control group did regular preseason training.
All 20 volleyball players were tested during the four weeks of training and for two weeks afterwards. Their vertical jump height was measured. So was the strength of their “jump” muscles (the knee extensor and ankle plantar flexor muscles).
Results showed that the players who got EMS and plyometric training jumped higher and had stronger “jump” muscles than before training. Their jump height even improved two weeks after the training program stopped. Meanwhile, the control group saw no improvements in strength or vertical jump.
The authors feel that this combination of EMS and jump training could be a useful preseason program for volleyball players. They suggest that EMS training may cause a nerve response that “programs” the muscles to be more efficient. The authors note, however, that it is possible that either plyometrics or EMS alone caused the gains in strength. More study is needed to find out.