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The purpose of this study was to compare strength training with and without superimposed electromyostimulation (EMS) on muscle strength and anaerobic power. Twenty-eight subjects were assigned to: weight+EMS (ES), weight (VOL), or control group (CG). ES and VOL performed 4 training sessions per week during 4 weeks on a knee extension machine (8 sets; 8 repetitions; 1-second concentric phase from 90 degrees to 0 degrees, 1-second eccentric phase from 0 degrees to 90 degrees , 1-second rest at 90 degrees; 3-minute rest between sets; 70% maximal voluntary contraction). Group ES received EMS in the concentric phase of each action (120 Hz, 400 microseconds). Before training, after training, and 2 weeks after the end of the training (detraining), maximal voluntary contraction, squat jump, countermovement jump (CMJ), countermovement jump with free arms (CMJA), and 20-m sprint time were analyzed. After the training period, ES and VOL increased their muscle strength (40.2% and 31.4%, respectively, p<0.001). After the detraining period, this gain remained above baseline values for ES and VOL (49.1% and 24.5%, respectively, p<0.001). Changes in muscle strength between baseline and detraining were higher in ES than in VOL (p<0.01). Anaerobic performance was not affected by training in any group, but percentage change between baseline and after training suggests that the CMJ and CMJA with free arms performance were impaired in ES with respect to VOL and CG. Superimposed EMS onto voluntary contractions increases strength more than voluntary training alone; nevertheless, a detraining period should be respected to observe this delayed adaptation. To improve anaerobic power with superimposed EMS, a complementary and specific work such as plyometrics should be carried out.

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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.