caa a22 4500 445352019 CHVBK 20180317142847.0 cr unu---uuuuu 170323e20110801xx s 000 0 eng 10.1007/s00221-011-2776-y doi (NATIONALLICENCE)springer-10.1007/s00221-011-2776-y EMG feedback tasks reduce reflexive stiffness during force and position perturbations [Elektronische Daten] [Patrick Forbes, Riender Happee, Frans van der Helm, Alfred Schouten] Force and position perturbations are widely applied to identify muscular and reflexive contributions to posture maintenance of the arm. Both task instruction (force vs. position) and the inherently linked perturbation type (i.e., force perturbations-position task and position perturbations-force tasks) affect these contributions and their mutual balance. The goal of this study is to explore the modulation of muscular and reflexive contributions in shoulder muscles using EMG biofeedback. The EMG biofeedback provides a harmonized task instruction to facilitate the investigation of perturbation type effects irrespective of task instruction. External continuous force and position perturbations with a bandwidth of 0.5-20Hz were applied at the hand while subjects maintained prescribed constant levels of muscular co-activation using visual feedback of an EMG biofeedback signal. Joint admittance and reflexive impedance were identified in the frequency domain, and parametric identification separated intrinsic muscular and reflexive feedback properties. In tests with EMG biofeedback, perturbation type (position and force) had no effect on joint admittance and reflexive impedance, indicating task as the dominant factor. A reduction in muscular and reflexive stiffness was observed when performing the EMG biofeedback task relative to the position task. Reflexive position feedback was effectively suppressed during the equivalent EMG biofeedback task, while velocity and acceleration feedback were both decreased by approximately 37%. This indicates that force perturbations with position tasks are a more effective paradigm to investigate complete dynamic motor control of the arm, while EMG tasks tend to reduce the reflexive contribution. The Author(s), 2011 Biofeedback nationallicence Neuromuscular control nationallicence Electromyography nationallicence Afferent feedback nationallicence Mechanical admittance nationallicence Reflexive impedance nationallicence Forbes Patrick Biomechanical Engineering, Department of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands aut Happee Riender Biomechanical Engineering, Department of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands aut van der Helm Frans Biomechanical Engineering, Department of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands aut Schouten Alfred Biomechanical Engineering, Department of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands aut Experimental Brain Research Springer-Verlag 213/1(2011-08-01), 49-61 0014-4819 213:1<49 2011 213 221 https://doi.org/10.1007/s00221-011-2776-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00221-011-2776-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Forbes Patrick Biomechanical Engineering, Department of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands aut NATIONALLICENCE 700 1- Happee Riender Biomechanical Engineering, Department of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands aut NATIONALLICENCE 700 1- van der Helm Frans Biomechanical Engineering, Department of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands aut NATIONALLICENCE 700 1- Schouten Alfred Biomechanical Engineering, Department of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands aut NATIONALLICENCE 773 0- Experimental Brain Research Springer-Verlag 213/1(2011-08-01), 49-61 0014-4819 213:1<49 2011 213 221 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer