Individual patterns of motor control in real-object control using a system with electromyographic biofeedback

Background. The introduction of software and hardware systems (SHS) with electromyographic (EMG) biofeedback into rehabilitation for the control of real physical objects is hindered by insufficient development of methodological support. Unlike screen-based and virtual trainers, such systems form a closed sensorimotor loop involving proprioceptive feedback, which requires special methodological approaches. In this regard, the study of the physiological support for the use of such systems in healthy volunteers, with a description of both subjective assessment of difficulty and objective performance characteristics, is relevant. Aim. To study the individual characteristics of motor control when using an SHS with EMG biofeedback for controlling a real physical object in healthy subjects, using objective performance indicators of exercise execution based on video analysis and subjective assessment of workload. Methods. The pilot observational cross-sectional study involved 26 subjects aged 18–35 years (15 women; 11 men) without neurological diseases or motor impairments. An SHS «BIOMOD» (Neuro MD LLC, Russia) with two Callibri myographic sensors and Android-based software was used. A modified radio-controlled car was controlled via EMG signals during contraction/relaxation of forearm muscles. Participants in two series of exercises (push/pull) controlled the movement of the car in two postural positions (sitting/standing) within a marked 5 m track. Objective assessment of the exercises was performed using video recordings. Subjective workload assessment was evaluated after completing the tasks using the NASA-TLX questionnaire (Russian-language adaptation). Results. In the sitting position, men showed a tendency toward shorter exercise completion time and lower error frequency; in the standing position, these sex differences were leveled out. The integrative indicator of control quality was characterized by relative stability: no statistically significant differences were found between groups. Analysis of subjective workload on the NASA-TLX scale showed that the most pronounced component was «Time Pressure», with moderate values of mental demand, physical effort, and a relatively low level of frustration. Correlation analysis revealed statistically significant relationships between individual NASA-TLX scales and objective control indicators in men; no such associations were found in women. The obtained data indicate the presence of sex differences in the structure of relationships between subjective perception of workload and the effectiveness of controlling a real object via EMG. Conclusion. The characteristics of motor control when controlling a real object via EMG in healthy volunteers were studied. The obtained data may serve as a basis for a methodology for using such devices in rehabilitation practice.