1. Introduction
The study group Strength Diagnostics and Movement Analysis (Institute for Sport Science and Sport Informatics, German Sport University Cologne) under the direction of Dr. Heinz Kleinöder found many positive effects of WB-EMS in various studies since 2006. Different programs such as training with different loading and sport-specific movements were intensified with simultaneous EMS and its effects were analysed subsequently. The questions ranged from acute physiological reactions (metabolic and hormonal) to long-term adaptations of strength (maximal force, maximal power, speed strength etc.). The transfer into athletic skills like sprinting, throwing and jumping was considered as well. All investigations were performed using low-frequency EMS.
2. Current state of research with WB-EMS
The following section presents several essential results of studies carried out over the course of the last years at the German Sport University Cologne, partly in cooperation with other research institutions. The results show the broad spectrum of EMS from rehabilitation to professional sports.
2.1 Shared study CHI: Herz- und Diabeteszentrum Bad Oeynhausen together with German Sport University Cologne
In this study, a conventional training (endurance training with spiroergometry) for patients with chronic heart disease (CHI) was replaced by WB-EMS (miha bodytec) for 8 muscle groups. 15 persons participated in a 6 months long training program (30 minutes, 2x/week, 4 s stimulation/4 s pause, 80 Hz, 400 µs). Effort of intensity 8 was individually chosen on a scale of up to 12.
Anaerobic capacity increased up to 96 % after 3 and 6 months, respectively (mean 25.35 %). Maximum oxygen uptake went up 24.6 % (VO2at 19.39 [± 5.3] ml/kg body weight [BW] before training and VO2at 24.25 [± 6.34] ml/kg BW after training improved significantly (p < 0.05)). Other sport forms were not able to produce comparable gains with CHI patients. Diastolic blood pressure dropped significantly (psyst < 0.05; pdiast < 0.001) and muscle size went up (14 %) without weight gain. WB-EMS was 100 % accepted without drop-outs. 14 patients reported a significantly improved performance in the final questionnaire, quality of life went up combined with a feeling of well-being. Moreover, an improvement of mood and a positive reflection of training were reported.
In summary, the improvement of objective performance with physiological and metabolic parameters surpassed the results after conventional aerobic training with CHI clearly. Thus the results show a considerable potential in cardiologic primary and secondary rehabilitation. Especially strongly limited patients profited extraordinarily.
2.2 Comparison and combination of different strength training methods
In this study, different strength training methods, i. e. hypertrophy, maximal force, strength endurance, vibration and whole body EMS (WB-EMS, miha bodytec) were compared with reference to their effects. WB-EMS was performed with medium intensity (60 %) so that a combination of WB-EMS with dynamic movements was possible. This arrangement was rarely investigated up to now, although especially dynamic movements are decisive for high speed in many sports.
80 sport students with at least 2 years of experience in strength training trained hamstrings and knee extensors at machines (GYM 80) in various groups with different programs (maximal force, hypertrophy, strength endurance 2x/week, 3 sets, 30 - 90 % of 1RM, 3 - 15 repetitions). The WB-EMS group performed lunges and squats without additional loading, but with electric stimulation (3 sets, 10 repetitions, 6 s with, 4 s without EMS, 85 Hz frequency, 350 µs impulse width, rectangular form). The training of all groups was standardized by a biofeedback system (Mechatronic). Thus each repetition had a clear specification, e. g. 2 s concentric and 2 s eccentric phase. Training took place 2x/week over 4 weeks. 2 tests were done at the beginning and at the end of the study at complex strength diagnostic machines equipped with force and distance sensors (Mechatronic). The task was to move the lever as fast as possible against 40 % and 60 % 1RM loading thus measuring power (P = F x v).
All strength training groups increased the power of knee extensors and hamstrings. A main result of this study was the increase of power by the factor force in all groups except for WB-EMS groups. Only the WB-EMS and mixed WB-EMS/hypertrophy groups showed significant results with reference to velocity increase. Power improved accordingly due to velocity increase about 30 %. This is highly important for sport practice since speed improved within a short time interval. An explanation for this result can be seen in the direct activation of fast muscle fibers. Moreover, the study also revealed that the combination of WB-EMS with dynamic movements is a promising combination for strength and speed training.
2.3 Applicability of EMS in professional football
This study intended to investigate the application possibilities of dynamic, low frequent WB-EMS on strength abilities, sprint and shot speed of professional soccer players.
22 professional players (25.6 ± 4.0 years, 81.1 ± 9.0kg, 182.3 ± 6.2 cm) of SC Fortuna Köln (Regionalliga West season 2011/12) were divided into an EMS group (EMSG, n=12), a jumping group (JPG, n=5) and a control group (CG, n=5). Most of them played in the
junior national league and had 3-5 years of experience in systematic strength training. EMSG had WB-EMS training 2x/week parallel to soccer and performed vertical jumps over 14 weeks. Low-frequency WB-EMS was applied with a waistcoat and a belt system with built-in electrodes (miha bodytec, Augsburg, Germany).
JPG and EMSG performed vertical jumps 2x/week. CG had no extra intervention but took only part in the team training (6 - 7 x/week). The study lasted 18 weeks in the second half of season 2011/2012. Pre- (wk0), in between (wk7), post- (wk14) and retest (wk18) were performed. The pre-test took place before the winter break in order to get representative data for the competitive phase. Tests included linear (30 m) and football-specific sprint abilities with specific changes of direction over 15 m. Jumping height was measured with squat jump (SJ), counter-movement-jump (CMJ) and Drop Jump (DJ). Maximum shot speed was determined after acceleration with one and three steps. Maximum force (1RM) of leg muscles was tested at the leg press (one-legged). Additionally IGF-1 and creatine kinase (CK) were measured in blood serum during tests, i. e. (pre), 15 - 30 min after (post) und 24 hours after training (24 h post).
All big muscle groups of the torso were stimulated with a vest (chest, back, abdominals). Gluteal muscles, thigh and calf muscles were trained with EMS using a belt system. Stimulation intensity was submaximal (80 Hz, 350 µs) according to Borg scale.
Within the first 14 weeks, players of EMSG absolved 2 training units each week on specific days. Afterwards, only 1 EMS Training took place between post- and retest. EMS Training started with a short warm-up of 2 - 3 minutes with players working at low intensity. The main part consisted of jumping under EMS stimulation (4 s with 2 s eccentric – 1 s isometric – 0.1 s concentric (explosive) – 1 s landing and stabilizing phase, 10 seconds pause in between). The players of JPG group performed the same program without EMS.
After 14 weeks of maximal force (1RM) within EMSG increased significantly (+22.42 ± 12.79 %) and even went up in the following 4 weeks until re-test (+30.07 ± 17.36 %). In contrast to this, JPG and CG showed no significant modifications. The increase of maximal force (EMSG) influenced vertical jumping performance positively (SJ +9.14 ± 9.36 %, CMJ +8.83 ± 8.17 %, DJindex: height/contact time +19.38 ± 16.13 %). While EMSG was able to maintain gains in maximal force and jumping performance, JPG and CG suffered significant losses in both parameters within the first 7 weeks of preparation period.
Considering sprinting abilities, there were also significant gains within EMSG. Within 7 weeks, linear sprint over 5 m and 10 m improved significantly, after 18 weeks we ended with -4.37 ± 4.41 % over 5 m und -2.61 ± 3.48 % over 10 m. There was no change over 20 m and 30 m. Values of JPG and CG remained stable without significant change. The same was true for the football specific sprint. EMSG was able to decrease sprinting time (15 m) after 14 weeks (-5.34 ± 5.73 %). JPG and CG revealed no significant changes.
With reference to shot speed (km/h), EMSG showed early improvements after 7 weeks and ended with significant changes after 14 weeks (one step: +13.3 ± 4.5 %; 3 steps: +6.0 ± 3.4 %) even increasing until re-test (1step +16.3 ± 6.7 %, 3 step +8.5 ± 7.8 %). In contrast to this, JPG had only one significant result (one step: +4.8 ± 3.3 %) and CG none.
The analysis of blood parameters revealed a significant rise in creatine kinase 24 hours only after EMS invention. There was no change in IGF-1 for both groups directly (15 - 30 min) and 24 hours after training.
The results of this study underline the importance of maximal force with reference to football specific speed. An increase in this parameter showed a positive influence on the development of jumping performance, sprinting and shot speed. An explanation for this can be found in literature, thus EMS inducing better recruitment of fast type II fibers. Since there was no significant gain in body weight and muscle size, improvement of maximum force can be attributed to neural adaptation mainly. This is further supported by the missing reaction of IGF-1.
In summary, we can conclude that WB-EMS in combination with football specific training complements classic loading in football very well enabling even professional players to improve in decisive parameters. The results also reveal that only 2 WB-EMS Training units of 12 min in addition to 6 - 7 football units/week are sufficient to develop specific performance effectively. Thus WB-EMS is a promising training alternative to conventional strength training in elite sports. In order to learn more about further applications, different studies in various sports and in the field of fundamental research are performed at German Sport University Cologne.
Dr. Heinz Kleinöder
Dr. Heinz Kleinöder has been working as a lecturer for the German Sporthochschule in Cologne at the Institute for Training Science and Sports Informatics since 1990. Since 2003 he has been head of the Department of Strength Diagnostics and Movement Science. His main areas of work include the diagnostics of conditional abilities in various competitive sports, the training of strength and technics with classical and innovative training methods. His long-term training activity in high-performance sports (tennis) is closely linked to his research, which focuses on the effects of a variety of strength training methods and training tools (including EMS and vibration) regarding health and performance. The latter has resulted in many publications. His transfers of the scientific results into practice took place in many sports and was passed on in numerous lectures at the Trainerakademie of the DOSB in Cologne.
Info
Working group on force diagnostics and movement research (Institute for Training Science and Sports Informatics, German Sports University Cologne)
First studies on EMS Training already in 2006, subject to research so far (selected):
- the efficacy of EMS Training in chronic heart failure patients
- the effects of EMS Training on movement speed
- the use of EMS Training in professional sports
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