Physiological reactions and adaptations to superimposed EMS during strength and endurance training.

Electromyostimulation (EMS) is an alternative training method and can be applied for an intensification of resistance or endurance training. This intensification is due to the specific pattern of motor-unit recruitment imposed by EMS, which is a nonselective, spatially fixed and temporally synchronous pattern. Previous studies showed that EMS is highly demanding on muscle metabolism, and can enhance energy expenditure and carbohydrate oxidation more than voluntary contraction. EMS strongly activates anaerobic glycolysis for energy production with lactate formation and acidifies more cytoplasm than voluntary contraction. Therefore, the superimposed application of EMS might cause greater metabolic stress, and hence, greater hormonal responses and adaptations. Further advantages on muscular strength and power could be achieved by whole body EMS devices that are able to stimulate several muscle groups simultaneously, e.g. muscle chains or agonist/antagonist during multi joint movement like squat exercise. There is a lack of studies dealing with dynamic exercise and superimposed EMS.

We investigated metabolic reactions and hormonal responses, as well as improvements in performance to superimposed EMS in different studies during cycling, loaded squats and exercises that are applied to improve sprinting, jumping, and throwing.

Main results show an high impact of EMS on metabolism during cycling but a smaller impact during loaded squat exercise. Hormonal responses are not influenced by EMS superimposed to loaded squat exercise (10 repetition maximum), however, specific muscular adaptations in maximum voluntary contraction and peak power occurred by superimposed EMS. However, superimposed EMS during cycling significantly increased hormone concentrations compared to sole cycling.