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Whole-body electromyostimulation (WB-EMS) is an extension of the EMS application known in physical therapy. In WB-EMS, body composition and skinfold thickness seem to play a decisive role in influencing the Ohmic resistance and therefore the maximum intensity tolerance. That is why the therapeutic success of (WB-)EMS may depend on individual anatomical parameters. The aim of the study was to find out whether gender, skinfold thickness and parameters of body composition have an influence on the maximum intensity tolerance in WB-EMS. [Participants and Methods] Fifty-two participants were included in the study. Body composition (body impedance, body fat, fat mass, fat-free mass) and skinfold thicknesses were measured and set into relation to the maximum intensity tolerance. [Results] No relationship between the different anthropometric parameters and the maximum intensity tolerance was detected for both genders. Considering the individual muscle groups, no similarities were found in the results. [Conclusion] Body composition or skinfold thickness do not seem to have any influence on the maximum intensity tolerance in WB-EMS training. For the application in physiotherapy this means that a dosage of the electrical voltage within the scope of a (WB-) EMS application is only possible via the subjective feedback (BORG Scale).
Many machine learning models show black box characteristics and, therefore, a lack of transparency, interpretability, and trustworthiness. This strongly limits their practical application in clinical contexts. For overcoming these limitations, Explainable Artificial Intelligence (XAI) has shown promising results. The current study examined the influence of different input representations on a trained model’s accuracy, interpretability, as well as clinical relevancy using XAI methods. The gait of 27 healthy subjects and 20 subjects after total hip arthroplasty (THA) was recorded with an inertial measurement unit (IMU)-based system. Three different input representations were used for classification. Local Interpretable Model-Agnostic Explanations (LIME) was used for model interpretation. The best accuracy was achieved with automatically extracted features (mean accuracy Macc = 100%), followed by features based on simple descriptive statistics (Macc = 97.38%) and waveform data (Macc = 95.88%). Globally seen, sagittal movement of the hip, knee, and pelvis as well as transversal movement of the ankle were especially important for this specific classification task. The current work shows that the type of input representation crucially determines interpretability as well as clinical relevance. A combined approach using different forms of representations seems advantageous. The results might assist physicians and therapists finding and addressing individual pathologic gait patterns
The difference in the efficacy of altered stimulation parameters in whole-body-electromyostimulation (WB-EMS) training remains largely unexplored. However, higher impulse frequencies (>50 Hz) might be most adequate for strength gain. The aim of this study was to analyze potential differences in sports-related performance parameters after a 10-week WB-EMS training with different frequencies. A total of 51 untrained participants (24.9 ± 3.9 years, 174 ± 9 cm, 72.4 ± 16.4 kg, BMI 23.8 ± 4.1, body fat 24.7 ± 8.1 %) was randomly divided into three groups: one inactive control group (CON) and two training groups. They completed a 10-week WB-EMS program of 1.5 sessions/week, equal content but different stimulation frequencies (training with 20 Hz (T20) vs. training with 85 Hz (T85)). Before and after intervention, all participants completed jumping (Counter Movement Jump (CMJ), Squat Jump (SJ), Drop Jump (DJ)), sprinting (5m, 10m, 30m), and strength tests (isometric trunk flexion/extension). One-way ANOVA was applied to calculate parameter changes. Post-hoc least significant difference tests were performed to identify group differences. Significant differences were identified for CMJ (p = 0.007), SJ (p = 0.022), trunk flexion (p = 0.020) and extension (p=.013) with significant group differences between both training groups and CON (not between the two training groups T20 and T85). A 10-week WB-EMS training leads to significant improvements of jump and strength parameters in untrained participants. No differences could be detected between the frequencies. Therefore, both stimulation frequencies can be regarded as adequate for increasing specific sport performance parameters. Further aspects as regeneration or long term effects by the use of different frequencies still need to be clarified.
Strength training in youth soccer has both a preventive and a
sports-specific component. Whole-body electromyostimulation
(WB-EMS) could represent an interesting time-saving add-on to
classical strength exercises in performance-oriented soccer. The
objective of this study was to find out whether a 10-week superimposed
WB-EMS training might have a more positive impact on
strength parameters in male youth elite soccer players than regular
athletic strength exercises alone. A total of 30 male youth soccer
players from a youth academy aged 15 to 17 years participated
in the study. Before and after the intervention, the isometric extension
and flexion forces of trunk and knee, and the hip abduction
and adduction forces were tested. Twelve players (control
group) absolved a conventional 20-minute strength training once
a week for a period of ten weeks. Eighteen players absolved the
same exercises but with superimposed WB-EMS. Blood creatine
kinase concentration was measured for training control. ANOVAs,
Friedman tests and post hoc t-tests were calculated (p =
0.05) to examine the strength development during the training period
between the groups. While we could not find significant
strength increases in the leg, hip and trunk muscles in the control
group (<4%), the strength of the WB-EMS group improved significantly
in 4 of the 6 muscle groups tested. In this group, the
strength of knee flexors increased significantly by 20.68 ±
21.55%, knee extensors by 31.43 ± 37.02%, hip adductors by
21.70 ± 12.86% and trunk flexors by 33.72 ± 27.43%. The rates
of strength increase are partly in line with other studies, partly
clearly higher, which might be explained by the athletically active
target group. A 10-week superimposed WB-EMS training improves
the strength of certain leg, hip and trunk muscles in male
adolescent elite soccer players to a greater extent than a pure athletic
strength training of the same duration.