Electric muscle stimulation (EMS) has been widely used in the rehabilitation of musculoskeletal injuries. Patterned electrical neuromuscular stimulation (PENS), a specific form of EMS, has been developed to better educate muscles to contract properly. The physiological efficacy of PENS has not been quantifiably identified. OBJECTIVES: The aim of this study is to determine the acute effect of one PENS training session (3 sets of 10 1-sec repetitions) on maximal isometric knee extensor (MVIC) torque production and surface EMG (sEMG) in healthy nonathlete college students. DESIGN: A randomized repeated-measures design was used in this study. METHODS: Twenty-two male college students participated in the study. All participants completed two training sessions, one with PENS and one without, in a randomized crossover design. RESULTS: One bout of PENS training significantly increased MVIC (3.1% ± 1.7%, p = 0.03) which was greater than the change in MVIC of the control group (p = 0.03). Control training did not alter MVIC but resulted in significant decrease in average sEMG amplitude (-7.8% ± 1.6%, p ≤ 0.01) and peak sEMG amplitude (-10.4% ± 2.7%, p ≤ 0.01). These reductions in sEMG following control training were significantly different from the PENS group (p = 0.03 and p ≤ 0.01). CONCLUSIONS: The findings suggest that strength training in conjunction with PENS can enhance torque production after just one bout of training. The increase in torque with no change in sEMG amplitude can be explained by increased motor unit synchronization or decreased cocontraction of antagonist muscles.

Als Werkzeuge der virtuellen Ergonomie dienen arbeitswissenschaftliche digitale Menschmodelle zur ergonomischen Gestaltung von Produkten und Arbeitsplätzen. Hohen Weiterentwicklungsbedarf bestimmen ihre Anwender vor allem für die integrierten Kraftanalysen. Eine Möglichkeit zur gelenkwinkel- und kraftrichtungsabhängigen Berechnung statischer Aktionskräfte ohne komplexe Muskelmodellierung basiert auf Muskelmomenten, welche in Maximalmomentkörpern modelliert werden. Die Arbeit schildert und diskutiert detailliert die Berechnung solcher Maximalmomentkörper am rechten Oberarm. Zwei separate Studien ermöglichen die Erstellung und Evaluierung. Im Rahmen der ersten Studie werden maximale Muskelmomente der Hauptbewegungen von Ellenbogen und Schulter in Abhängigkeit der Gelenkwinkelstellungen erfasst und in Polynomen interpoliert. Durch diese gelenkwinkelabhängigen Momente können die Maximalmomentkörper modelliert werden. Im Rahmen der zweiten Studie werden wirkenden Muskelmomente mit den prognostizierten verglichen. Die Ergebnisse zeigen, dass die Maximalmomentkörper die wirkenden Muskelmomente bei maximalen Kraftaufbringungen im Mittel auf etwa 2 % genau vorhersagen, wobei einen Streubereich von etwa 50 % zu beachten ist. Der Streubereich ist dabei durch eine kritische Diskussion erklärbar und unter anderem den psychophysischen Verfahren einer Maximalkraftmessung zurechenbar. / Digital human models as tools of virtual ergonomics serve for the design of products and workplaces. High demands for further development determine their users, for the integrated force analyzes. One way to calculate joint-angle- and force-direction-dependent static forces without complex muscle modeling is based on muscle torques, which are modeled in maximum torque bodies known as “M-Potatos”. This work describes and discusses the calculation of such maximum torque bodies for the right upper arm. Two separate studies allow the preparation and evaluation. The first study explore the maximum muscle torques within the main movement directions of the elbow and shoulder and interpolate them as polynomials of the joint angle position. With these polynomials, the maximum torque bodies can be modeled. The second study compared effective muscle torques with those predicted. The results show that the maximum torque bodies predict the effective muscle moments at maximum isometric force application on average at about 2%, with a range of about 50% to be considered. The range can be explained by a critical discussion and, among other things, attributable to the psychophysical method of a maximum force measurement.