Short-term effect of plyometrics and strength training with and without superimposed electrical stimulation on muscle strength and anaerobic performance: A randomized controlled trial. Part II.

The purpose of this study was to compare the effects of combined strength and plyometric training with or without superimposed electromyostimulation (EMS) on muscle strength and anaerobic power. Twenty-nine subjects were randomly assigned to weight+plyometrics+EMS (EP), weight+plyometrics (VP), and control group (CG). Weight+plyometrics+EMS and VP performed 2 plyometric sessions and 2 weight training sessions per week throughout 4 weeks on a knee extension machine. Weight+plyometrics+EMS received EMS throughout the concentric phase of each action (120 Hz, 400 microseconds). Before, after training, and 2 weeks after the end of the training (detraining), maximal voluntary contraction, squat jump, countermovement jump, countermovement jump with free arms, and 20-minute sprint time were analyzed. After the training period, EP and VP increased their muscle strength (28.6 and 22.3%, respectively; p<0.001). After the detraining period, this gain remained above baseline values (28.1 and 18.0%, respectively; p<0.001 and p<0.01). After training and detraining, muscle strength was higher in EP than in VP (p<0.05). Vertical jump height was not modified for whichever group or test, except for the countermovement jump height with free arms, where a decrease for EP was observed after training (-6.3%; p<0.001) and detraining (-5.5%; p<0.001). Sprint performance improved in all groups in the detraining test (-0.8%; p<0.05). If a low number of training sessions are carried out, superimposed EMS leads to a higher strength gain than voluntary training alone. However, if anaerobic power is an important aim of the training, EMS should be applied isometrically instead of superimposed EMS and combined with plyometrics.