Physical Strain Leads To Jaw Clenching And Frowning Body Language
Christopher Philip
Resent research published in the Journal of Sports Science and Medicine found direct evidence that frowning and jaw clenching is related to incremental workload and effort during cycling.
This might not seem particularly relevant in nonverbal communication, however, jaw clenching has been anecdotally connected to emotional discomfort for quite some time without any empirical support.
In this particular study, jaw clenching was found to be linearly related to perception of physical effort and muscles strain of the lower limbs. So as a person exerted more effort into cycling, their facial electromyography (EMG) readings increased.
The EMG measured activity of the corrugator supercilii (CS), masseter and vastus lateralis (VL) muscles.
“Furthermore,” say the researchers “facial muscle activity increased significantly during high-intensity exercise — The present investigation supports the view that facial EMG activity reflects the perception of effort. The jaw clenching facial expression can be
considered an important factor for improving the reporting of perceived effort during high-intensity exercise in males and females.”
This evidence also lends support to the idea that frowning and jaw clenching is also related to emotional strain such that a person, when undergoing emotional stress, is likely to show this strain in the muscle actions of the face. However, this is leading and not always reflective of reality. As people are often keen to hide their emotions, it’s equally likely for a person to stifle their visible emotional reactions.
While it is a leap to assume that jaw clenching is a sign of emotional distress, context permitting, should no physical stress be occurring, yet jaw clenching evident, we could reasonably assume that it is due to emotional rather than physical strain.
At the very least, however, this particular research lends support to the idea that facial frowning and jaw clenching is, as shown here, a strong indicator of physical strain. The leap, and one we can likely assume is that jaw clenching is also the result of emotional strain.
Image Credit: Official U.S. Navy Page
Resources
Huang, Ding-Hau; Shih-Wei Chou; Yi-Lang Chen and Wen-Ko Chiou. Frowning and Jaw Clenching Muscle Activity Reflects the Perception of Effort During Incremental Workload Cycling. Journal of Sports Science and Medicine. 2019. 13: 921-928.