Activation patterns of facial muscles were recently characterized in young males by multi-channel surface electromyography (Schumann et al. 2010). Up to now it is not known if there are important differences in comparison to females. Therefore, 25 healthy female volunteers (mean age 23.3 years, SD +/- 2.3) were also examined by the 48-channel surface EMG technique (monopolar, 10-700 Hz, 3000 samples/s, resolution of 2.44 µV/bit, see Schumann et al. 2010) while performing 31 defined facial movements. EMG curves were visually checked, quantified by power spectral analysis and normalized. The mean EMG amplitudes (square root of the spectral power) of the facial muscles were demonstrated in muscle activation profiles (box-plots arranged with respect to the side of the face). Results were compared to the activation profiles of 25 young healthy men (mean age 26 years, SD +/- 3.4) examined before. The EMG data of the males were re-analyzed by the examiner of the female group.

It is not surprisingly that the activation profiles of men and women are alike with regard to the same facial movement. On the other hand, there were found statistically significant differences between females and males in some facial muscles (electrode positions) and some facial movements verified by the non-parametric Mann-Whitney-U-Test for un-paired samples (p<0.05). During the exercise “pressing lips together” as well as “exhaling forcefully with moderate closed lips” (a more diffuse whistling) the involved muscles of the male group show significantly higher EMG activities than that of the females. In contrast, during “contracting the eyebrows” significantly higher EMG activities were found in females for the zygomatic, levator labii and mentalis muscles. The males group again demonstrated higher EMG activities in the inferior part of the orbicularis oculi muscles during “smiling only on the right side” as well as “…left side” respectively. All in all the results demonstrate similarities and differences between females and males with respect to facial muscle activation patterns. Therefore, EMG activity profiles of different genders should not be pooled in general to create EMG reference data. Further investigations are necessary.