Facial EMG channels and corresponding facial regions (lower face—LF, upper face—UF) and monitored location.

Facial EMG channels and corresponding facial regions (lower face—LF, upper face—UF) and monitored location.</p

Facial sEMG during different exercise intensities.

Capture of facial expression (a); Raw signal from the zygomaticus major muscle (Ch8) (b); The estimated Wlech’s power spectral density (PSD) (c); Corresponding accelerometer and gyroscope 3-axis data (d and e).</p

Experimental setup.

The sEMG multi-electrode array sticker placement on a participant, with the channel numbers corresponding to each electrode, in both upper and lower facial regions. Also shown are the VL EMG unit and the DAU supporting 16-channel facial EMG recording and acceleration data collection of the head.</p

Neutral facial expression ratio (NFER) calculated for all 16 channels during the test, indicating signal’s stability throughout the intensity range (N = 6).

Neutral facial expression ratio (NFER) calculated for all 16 channels during the test, indicating signal’s stability throughout the intensity range (N = 6).</p

Examples of post-processing of data recorded of voluntary smiles during the exercise test.

Differential sEMG (filtered) data from electrode pairs (A); 3 fastICA that was applied upon the signals recorded from all 16 channels (B); Corresponding heatmaps that depict the activated muscles resulted from the ICA analysis (C); The cycling protocol with marks of the instructed voluntary smiles (shadowed green) (D).</p

Correlation coefficient table between normalized RMS values of sEMG data of each channel and RMS of VL muscle.

Correlation coefficient table between normalized RMS values of sEMG data of each channel and RMS of VL muscle.</p

Average±SD of normalized RMS values of sEMG data from the frontalis muscle during voluntary smiles along the exercise test (black line) and the average RMS values of the VL muscle (grey line) (N = 6).

Average±SD of normalized RMS values of sEMG data from the frontalis muscle during voluntary smiles along the exercise test (black line) and the average RMS values of the VL muscle (grey line) (N = 6).</p

Comparison between various facial expression studies during physical tasks using facial electromyography.

Comparison between various facial expression studies during physical tasks using facial electromyography.</p