Physiological responses and perceived exertion during cycling with superimposed electromyostimulation

Whole-Body Electromyostimulation Impacts Physiological Responses During Aerobic Running: A Randomized Trial

Objective: The aim of the current study was to evaluate the physiological and metabolic responses to running with whole-body electromyostimulation (wbEMS) compared to running without electromyostimulation (control, CG). Methods: Twenty healthy participants (9 male/11 female, age 42 ±7 years) conducted an incremental step test with respiratory gas analysis until exhaustion. Trials were conducted as wbEMS and CG in a random order. As outcome measures, (A) objective total exhaustion, (B) athletic responses (max. time and velocity) and (C) physiological and metabolic responses (V'O2/ kg, V'E, EE, RER, lactate) were compared. (D) The impact on the skeletal muscle was assessed prior, 48 h & 72 h after trial. Results: During both trials, participants (A) ran until total exhaustion. Nonetheless, (B) time and velocity till exhaustion as well as (C) RER prior to the first lactate threshold and V'E were reduced with wbEMS. All other correlates did not differ significantly between wbEMS and CG. Following 48 h and 72 h after the trial with wbEMS, (D) the impact on the skeletal muscle was 7- to 9-fold higher compared to baseline values. Values differed significantly to those after running without wbEMS. Conclusion: With the additional stimulation during voluntary activation, wbEMS induces earlier fatigue and a shift in energy metabolism toward fat utilization. Even during aerobic endurance tasks, a great impact on the skeletal muscle indicated by the rise in CK could be observed which promotes wbEMS as an alternative training stimulus that is easy-to-apply and effective during endurance training.

Running with whole-body electromyostimulation improves physiological determinants of endurance performance - a randomized control trial

BACKGROUND

This study aimed to evaluate the physiological and metabolic adaptations to an eight-week running intervention with whole-body electromyostimulation (wbEMS) compared to running without wbEMS.

METHODS

In a randomized controlled trial (RCT), 59 healthy participants (32 female/ 27 male, 41 ± 7 years, rel.V̇O2max 40.2 ± 7.4 ml/min/kg) ran twice weekly à 20 min for eight weeks either with a wbEMS suit (EG) or without wbEMS (control group, CG). Before and after the intervention, (i) rel.V̇O2max, heart rate and time to exhaustion were recorded with an incremental step test with an incremental rate of 1.20 km/h every 3 min. They were interpreted at aerobic and (indirect) anaerobic lactate thresholds as well as at maximum performance. (ii) Resting metabolic rate (RQ) as well as (iii) body composition (%fat) were assessed.

RESULTS

Following the intervention, V̇O2max was significantly enhanced for both groups (EG ∆13 ± 3%, CG ∆9 ± 3%). Velocity was elevated at lactate thresholds and maximum running speed (EG ∆3 ± 1%, CG ∆2 ± 1%); HRmax was slightly reduced by -1 beat/min. No significant changes were observed for time until exhaustion and lactate. RQ was significantly enhanced following both trainings by + 7%. %fat was reduced for both groups (EG ∆-11 ± 3%, CG ∆-16 ± 5%), without any changes in body mass. Results did not differ significantly between groups.

CONCLUSIONS

Both interventions had a positive impact on aerobic power. The rightward shift of the time-velocity graph points towards improved endurance performance. The effects of wbEMS are comparable to those after high-intensity training and might offer a time-efficient alternative to affect physiological and metabolic effects.

TRIAL REGISTRATION

German Clinical Trials Register, ID DRKS00026827, date 10/26/21.

Effects of electromyostimulation on performance parameters in sportive and trained athletes: A systematic review and network meta-analysis

This systematic review and network meta-analysis aimed to evaluate the effectiveness of different electromyostimulation (EMS) training interventions on performance parameters in trained athletes. The research was conducted until may 2021 using the online databases PubMed, Web of Science, Cochrane and SPORTDiscus for studies with the following inclusion criteria: (a) controlled trials, (b) EMS trials with at least one exercise and/or control group, (c) strength and/or jump and/or sprint and/or aerobic capacity parameter as outcome (d) sportive/trained subjects. Standardized mean differences (SMD) with 95% confidence interval (CI) and random effects models were calculated. Thirty-six studies with 1.092 participants were selected and 4 different networks (strength, jump, sprint, aerobic capacity) were built. A ranking of different exercise methods was achieved. The highest effects for pairwise comparisons against the reference control "active control" were found for a combination of resistance training with superimposed EMS and additional jump training (outcome strength: 4.43 SMD [2.15; 6.70 CI]; outcome jump: 3.14 SMD [1.80;4.49]), jump training with superimposed whole-body electromyostimulation (WB-EMS) (outcome sprint: 1.65 SMD [0.67; 2.63 CI] and high intensity bodyweight resistance training with superimposed WB-EMS (outcome aerobic capacity: 0.83 SMD [-0.49; 2.16 CI]. These findings indicate that the choice of EMS-specific factors such as the EMS application mode, the combination with voluntary activation, and the selection of stimulation protocols has an impact on the magnitude of the effects and should therefore be carefully considered, especially in athletes. Superimposed EMS with relatively low volume, high intensity and outcome-specific movement pattern appeared to positively influence adaptations in athletes.

Superimposing neuromuscular electrical stimulation onto voluntary contractions to improve muscle strength and mass: a systematic review

Training and rehabilitation programs involving neuromuscular electrical stimulation superimposed onto voluntary contractions (NMES+) have gained popularity in the last decades. Yet, there is no clear consensus on the effectiveness of such intervention. The aim of this review was to evaluate the effect of chronic exposure to NMES+ on muscle strength and mass compared to conventional volitional training or passive electrical stimulation alone. Two authors conducted an electronic search to identify randomized controlled trials that investigated the effect of NMES+ training, involved healthy participants or orthopaedic patients, detailed a well-defined NMES training protocol, and provided outcomes related to skeletal-muscle strength and/or mass. The authors extracted data on participants, intervention characteristics, muscle-related outcomes, and assessed the methodological quality of the studies.A total of twenty-four studies were included in the review. The majority of these reported an increase in muscle strength following training with NMES+ compared to an equivalent voluntary training or passive NMES training. The highest improvements were found when NMES was superimposed on sub-maximal exercises involving both concentric and eccentric contractions. Only two studies reported an increase in muscle mass after NMES+ intervention, while no significant improvements were found in two other studies.This review indicated that chronic exposure to NMES+ determines muscle strength improvements greater or equal compared to volitional training alone. However, differences in the methodological characteristics of the stimulation and the type of exercise associated with NMES+, revealed significant discrepancies in the results. A deeper understanding of the neurophysiological adaptations to NMES+ is crucial to fully explain the muscle-related enhancement resulting from such intervention.

Acute Effect of Electromyostimulation Superimposed on Running on Maximal Velocity, Metabolism, and Perceived Exertion

Electromyostimulation has been shown to intensify exercise when superimposed on cycling. However, little is known about the application during running, which might help to prevent injuries linked to high running volumes, as intensification of running allows for a reduction in training volume. Therefore, the purpose of the study was to examine the effects of electromyostimulation superimposed on running. Men who were no younger than 18 and no older than 35 were eligible for inclusion in the study. Exclusion criteria were previous experience with electromyostimulation training, the presence of a contraindication according to the manufacturer, or a contraindication to physical activity. A sample of 22 healthy males with an ordinary performance capability accomplished three similar cardiopulmonary treadmill tests until exhaustion in a crossover study design that included lactate measurements and interrogations of perceived exertion. The first test was conducted without electromyostimulation and was followed in a randomized order by the second and the third test condition with 30 or 85 Hz stimulation, respectively, of the lower body. Superimposed electromyostimulation significantly reduced the maximal achieved velocity (control 15.6 ± 1.1 vs. 30 Hz 15.1 ± 1.2, p = 0.002; vs. 85 Hz 14.9 ± 1.1 km/h, p < 0.001), increased the perceived exertion at 10, 12 and 14 km/h (85 Hz + 0.7, p = 0.036; +0.9, p = 0.007; +1.3, p < 0.001; 30 Hz + 0.7, p = 0.025; +1.0, p = 0.002; +1.2, p < 0.001), and induced a significantly higher oxygen uptake at 8 km/h (85 Hz + 1.1, p = 0.006; 30 Hz + 0.9 mL·min−1·kg−1, p = 0.042), 10 km/h (30 Hz + 0.9 mL·min−1·kg−1, p = 0.032), and 14 km/h (85 Hz + 1.0 mL·min−1·kg−1, p = 0.011). Both electromyostimulation conditions significantly limited the maximal lactate level (30 Hz p = 0.046; 85 Hz p < 0.001) and 85 Hz also the recovery lactate level (p < 0.001). Superimposed electromyostimulation is feasible and intensifies running. Coaches and athletes could benefit from the increased training stimulus by reducing running velocity or volume, by combining endurance and strength training, and also by inducing better adaptations while maintaining the same velocity or volume. Therefore, electromyostimulation superimposed on running could be an interesting training tool for runners.

Whole-Body EMS Superimposed Walking and Nordic Walking on a Treadmill-Determination of Exercise Intensity to Conventional Exercise

Electrical muscle stimulation (EMS) is an increasingly popular training method and has become the focus of research in recent years. New EMS devices offer a wide range of mobile applications for whole-body EMS (WB-EMS) training, e.g., the intensification of dynamic low-intensity endurance exercises through WB-EMS. The present study aimed to determine the differences in exercise intensity between WB-EMS-superimposed and conventional walking (EMS-CW), and CON and WB-EMS-superimposed Nordic walking (WB-EMS-NW) during a treadmill test. Eleven participants (52.0 ± years; 85.9 ± 7.4 kg, 182 ± 6 cm, BMI 25.9 ± 2.2 kg/m²) performed a 10 min treadmill test at a given velocity (6.5 km/h) in four different test situations, walking (W) and Nordic walking (NW) in both conventional and WB-EMS superimposed. Oxygen uptake in absolute (VO₂) and relative to body weight (rel. VO₂), lactate, and the rate of perceived exertion (RPE) were measured before and after the test. WB-EMS intensity was adjusted individually according to the feedback of the participant. The descriptive statistics were given in mean ± SD. For the statistical analyses, one-factorial ANOVA for repeated measures and two-factorial ANOVA [factors include EMS, W/NW, and factor combination (EMS^*W/NW)] were performed (α = 0.05). Significant effects were found for EMS and W/NW factors for the outcome variables VO₂ (EMS: p = 0.006, r = 0.736; W/NW: p < 0.001, r = 0.870), relative VO₂ (EMS: p < 0.001, r = 0.850; W/NW: p < 0.001, r = 0.937), and lactate (EMS: p = 0.003, r = 0.771; w/NW: p = 0.003, r = 0.764) and both the factors produced higher results. However, the difference in VO₂ and relative VO₂ is within the range of biological variability of ± 12%. The factor combination EMS^*W/NW is statistically non-significant for all three variables. WB-EMS resulted in the higher RPE values (p = 0.035, r = 0.613), RPE differences for W/NW and EMS^*W/NW were not significant. The current study results indicate that WB-EMS influences the parameters of exercise intensity. The impact on exercise intensity and the clinical relevance of WB-EMS-superimposed walking (WB-EMS-W) exercise is questionable because of the marginal differences in the outcome variables.

Cardiorespiratory, Metabolic and Perceived Responses to Electrical Stimulation of Upper-Body Muscles While Performing Arm Cycling

This study was designed to assess systemic cardio-respiratory, metabolic and perceived responses to incremental arm cycling with concurrent electrical myostimulation (EMS). Eleven participants (24 ± 3 yrs; 182 ± 10 cm; 86 ± 16.8 kg) performed two incremental tests involving arm cycling until volitional exhaustion was reached with and without EMS of upper-body muscles. The peak power output was 10.1% lower during arm cycling with (128 ± 30 W) than without EMS (141 ± 25 W, p = 0.01; d = 0.47). In addition, the heart rate (2-9%), oxygen uptake (7-15%), blood lactate concentration (8-46%) and ratings of perceived exertion (4-14%) while performing submaximal arm cycling with EMS were all higher with than without EMS (all p < 0.05). Upon exhaustion, the heart rate, oxygen uptake, lactate concentration, and ratings of perceived exertion did not differ between the two conditions (all p > 0.05). In conclusion, arm cycling with EMS induced more pronounced cardio-respiratory, metabolic and perceived responses, especially during submaximal arm cycling. This form of exercise with stimulation might be beneficial for a variety of athletes competing in sports involving considerable generation of work by the upper body (e.g., kayaking, cross-country skiing, swimming, rowing and various parasports).

Modulation of spinal excitability following neuromuscular electrical stimulation superimposed to voluntary contraction

Purpose

Neuromuscular electrical stimulation (NMES) superimposed on voluntary muscle contraction has been recently shown as an innovative training modality within sport and rehabilitation, but its effects on the neuromuscular system are still unclear. The aim of this study was to investigate acute responses in spinal excitability, as measured by the Hoffmann (H) reflex, and in maximal voluntary contraction (MVIC) following NMES superimposed to voluntary isometric contractions (NMES + ISO) compared to passive NMES only and to voluntary isometric contractions only (ISO).

Method

Fifteen young adults were required to maintain an ankle plantar-flexor torque of 20% MVC for 20 repetitions during each experimental condition (NMES + ISO, NMES and ISO). Surface electromyography was used to record peak-to-peak H-reflex and motor waves following percutaneous stimulation of the posterior tibial nerve in the dominant limb. An isokinetic dynamometer was used to assess maximal voluntary contraction output of the ankle plantar flexor muscles.

Results

H-reflex amplitude was increased by 4.5% after the NMES + ISO condition (p < 0.05), while passive NMES and ISO conditions showed a decrease by 7.8% (p < 0.05) and no change in reflex responses, respectively. There was no change in amplitude of maximal motor wave and in MVIC torque during each experimental condition.

Conclusion

The reported facilitation of spinal excitability following NMES + ISO could be due to a combination of greater motor neuronal and corticospinal excitability, thus suggesting that NMES superimposed onto isometric voluntary contractions may provide a more effective neuromuscular stimulus and, hence, training modality compared to NMES alone.

Seven Weeks of Jump Training with Superimposed Whole-Body Electromyostimulation Does Not Affect the Physiological and Cellular Parameters of Endurance Performance in Amateur Soccer Players

Intramuscular density of monocarboxylate-transporter (MCT) could affect the ability to perform high amounts of fast and explosive actions during a soccer game. MCTs have been proven to be essential for lactate shuttling and pH regulation during exercise and can undergo notable adaptational changes depending on training. The aim of this study was to evaluate the occurrence and direction of potential effects of a 7-weeks training period of jumps with superimposed whole-body electromyostimulation on soccer relevant performance surrogates and MCT density in soccer players. For this purpose, 30 amateur soccer players were randomly assigned to three groups. One group performed dynamic whole-body strength training including 3 x 10 squat jumps with WB-EMS (EG, n = 10) twice a week in addition to their daily soccer training routine. A jump training group (TG, n = 10) performed the same training routine without EMS, whereas a control group (CG, n = 8) merely performed their daily soccer routine. 2 (Time: pre vs. post) x 3 (group: EG, TG, CG) repeated measures analyses of variance (rANOVA) revealed neither a significant time, group nor interaction effect for VO₂peak, Total Time to Exhaustion and La_max as well as MCT-1 density. Due to a lack of task-specificity of the underlying training stimuli, we conclude that seven weeks of WB-EMS superimposed to jump exercise twice a week does not relevantly influence aerobic performance or MCT density.

(Whole-Body) Electromyostimulation, Muscle Damage, and Immune System: A Mini Review

Exercise-induced muscular damage (EIMD) is a well-known phenomenon in exercise medicine that is closely related to the type and intensity of training, with especially eccentric training content providing various physiological irritations, including mechanical as well as metabolic. Besides the increase in markers of muscular damage, such as creatine kinase (CK) and myoglobin (Mb), several physiological shifts trigger a kind of stepwise repair chain reactions lasting over a time course from several hours to days. Subsequent inflammatory processes are closely related to muscular damage with decisive influence on physiological repair mechanisms, as indicated by an increased invasion of immune cells and typical patterns of pro- and anti-inflammatory cytokines. Previously, whole-body electromyostimulation (WB-EMS) showed significant, partly extreme distractions in markers of muscular damage lasting over several days. Because of the large area of stimulated muscle mass and a relatively high proportion of eccentric movements, initially too intense WB-EMS is predisposed to produce serious changes on several physiological levels due to its unfamiliar muscular strain. Therefore, it is the aim of this short review to focus on the possible immunological side effects of this aspiring training technology. As the number of original investigations in this field is rather small, we will include data from other studies about the relation of exercise-induced muscle damage and immune regulation.

Efficacy and Safety of Low Frequency Whole-Body Electromyostimulation (WB-EMS) to Improve Health-Related Outcomes in Non-athletic Adults. A Systematic Review

Exercise positively affects most risk factors, diseases and disabling conditions of middle to advanced age, however the majority of middle-aged to older people fall short of the exercise doses recommended for positively affecting cardio-metabolic, musculoskeletal and neurophysiological fitness or disabling conditions. Whole-Body Electromyostimulation (WB-EMS) may be a promising exercise technology for people unable or unmotivated to exercise conventionally. However, until recently there has been a dearth of evidence with respect to WB-EMS-induced effects on health-related outcomes. The aim of this systematic review is to summarize the effects, limitations and risks of WB-EMS as a preventive or therapeutic tool for non-athletic adults. Electronic searches in PubMed, Scopus, Web of Science, PsycINFO, Cochrane and Eric were run to identify randomized controlled trials, non-randomized controlled trials, meta-analyses of individual patient data and peer reviewed scientific theses that examined (1) WB-EMS-induced changes of musculoskeletal risk factors and diseases (2) WB-EMS-induced changes of functional capacity and physical fitness (3) WB-EMS-induced changes of cardio-metabolic risk factors and diseases (4) Risk factors of WB-EMS application and adverse effects during WB-EMS interventions. Two researchers independently reviewed articles for eligibility and methodological quality. Twenty-three eligible research articles generated by fourteen research projects were finally included. In summary, thirteen projects were WB-EMS trials and one study was a meta-analysis of individual patient data. WB-EMS significantly improves muscle mass and function while reducing fat mass and low back pain. Although there is some evidence of a positive effect of WB-EMS on cardio-metabolic risk factors, this aspect requires further detailed study. Properly applied and supervised, WB-EMS appears to be a safe training technology. In summary, WB-EMS represents a safe and reasonable option for cohorts unable or unwilling to join conventional exercise programs. However, much like all other types of exercise, WB-EMS does not affect every aspect of physical performance and health.

Chronic effects of superimposed electromyostimulation during cycling on aerobic and anaerobic capacity

PURPOSE

To examine if chronic endurance training by means of simultaneously applied, superimposed electromyostimulation (EMS) can be used to improve performance and physiological core parameters compared to the traditional cycling.

METHODS

Twenty-one male subjects (VO_2peak 55.2 ± 5.1 ml min^- 1 kg^- 1) were assigned to either a cycling (C) or cycling with superimposed EMS (C + E) group. Before and after the 4-week training period, including 14 sessions of moderate cycling [60 min at 60% peak power output (PPO)], participants performed a 20-min time-trial, a step test to exhaustion, a 30-s isokinetic sprint test, and maximum force- and power-tests. Markers of muscle damage and metabolic condition were assessed during the training period.

RESULTS

Step test results revealed increases in PPO, VO_2peak, lactate threshold 1, and the anaerobic threshold for both groups (p < 0.05). Mean power output (MPO) obtained from time-trial was improved in C and C + E (p < 0.05). Isokinetic sprint test revealed increased PPO in both groups, whereas MPO was only changed in C (p < 0.05). Strength parameters were unaffected. Although metabolic stimuli and markers of muscle damage were higher in C + E compared to C, improvements of endurance performance and capacity were not significantly different between C and C + E.

CONCLUSIONS

Despite a higher metabolic, respiratory, and muscular demand, chronic additional superimposed EMS during cycling does not result in superior improvements in endurance and strength performance compared to the traditional cycling.

Acute metabolic, hormonal and psychological responses to cycling with superimposed electromyostimulation

PURPOSE

The purpose of the present study was to evaluate the effects of superimposed electromyostimulation (E) during cycling on the acute hormonal and metabolic response, as E might be a useful tool to intensify endurance training without performing high external workloads.

METHODS

Thirteen subjects participated in three experimental trials each lasting 60 min in a randomized order. (1) Cycling (C), (2) cycling with superimposed E (C + E) and (3) E. Human growth hormone (hGH), testosterone and cortisol were determined before (pre) and 0', 30', 60', 240' and 24 h after each intervention. Metabolic stimuli and perturbations were characterized by lactate and blood gas analysis (pH, base excess, bicarbonate, partial pressure of oxygen, partial pressure of carbon dioxide). Furthermore, changes of the person's perceived physical state were determined.

RESULTS

C + E caused the highest increases in cortisol and hGH, followed by C and E. Testosterone levels showed no significant differences between C + E and C. Metabolic stress was highest during C + E, followed by C and E. C + E was also the most demanding intervention from an athlete's point of view.

CONCLUSION

As cortisol and hGH are known to react in an intensity dependent manner, the present study showed that superimposed E is a useful method to intensify endurance training, even when performing low to moderate external workloads. Even at lower exercise intensities, additional E may allow one to induce a high (local) stimulus. It can be speculated, that these acute hormonal increases and metabolic perturbations, might play a positive role in optimizing long-term training adaptations, similar to those of intense training protocols.