Biofeedback effectiveness to reduce upper limb muscle activity during computer work is muscle specific and time pressure dependent

The muscle activity (%max-EMGrms) from (a) right TRA, (b) left TRA, and (c) right EDC during biofeedback from right TRA or EDC or during control sessions with no biofeedback (CON). EDC, right m. extensor digitorum communis; TRA, right m. trapezius; EMG, electromyography; MMG, mechanomyography; %max-EMGrms, maximal EMGrms obtained during MVC. Values are mean±SD, n=11. ∗Indicate significant difference. Note: the y axis does not origin at 0 in c).

The muscle activity (%max-EMGrms) from (a) right TRA and (b) left TRA during overall biofeedback when working with time constraint, no time constraint, or during control sessions with no biofeedback (CON). TRA, right m. trapezius; TC, time constraint; No TC, no time constraint; %max-EMGrms, maximal EMGrms obtained during MVC. Values are mean±SD, n=11. ∗Indicate significant difference.

The subjective evaluation of the usefulness of the biofeedback by answering the question “Was the biofeedback useful?” by either answering I fully disagree (1), I partly disagree (2), I partly agree (3), or I fully agree (4) after ended work session. Answers within the two biofeedback muscles, biofeedback modes, and working conditions were pooled. The box-and-whisker plot summarizes the Δ: difference in usefulness of biofeedback and work type factors (left y axis) and the usefulness of all biofeedback sessions (right y axis). For Δ usefulness, the subtraction order is indicated on the categorical axis. Bold line indicates the median (50th centile), error bars indicate the 95% central range (2.5 and 97.5centiles), the maximal and minimal box values indicate the quartiles (25 and 75centiles), and open circles indicate values outside the 95% central range. EDC, right m. extensor digitorum communis; TRA, right m. trapezius; TC, time constraint; No TC, no time constraint; EMG, electromyography; MMG, mechanomyography.

The production of (a) graphs and (b) mouse clicks during standardized computer work in biofeedback sessions (BIO) and control session (CON) with time constraint (TC) or no time constraint (No TC). Values are mean±SD, n=11. ∗Indicate significant difference. Note: the y axis does not origin at 0.