Muscle tension in generalized anxiety disorder: Elevated muscle tonus or agitated movement?

Summary & key facts

The study recorded electrical muscle activity (EMG) from the forehead (frontalis) and calf (gastrocnemius) in 18 women with generalized anxiety disorder (GAD) and 19 nonanxious women during baseline, a lab stressor, and recovery. The GAD group had higher average EMG levels, and during the stressor they showed a drop in variability of frontalis activity. For both groups, gastrocnemius activity increased in average level and variability and decreased in skewness during the stressor. The authors conclude these results point to elevated muscle tonus in clinically anxious people and different muscle responses to stress across muscles.

Key facts:

• The study included 18 women with generalized anxiety disorder (GAD) and 19 nonanxious women, for a total of 37 participants.
• EMG was recorded from two muscles: the frontalis (forehead) and the gastrocnemius (calf).
• The GAD group had greater mean (average) EMG levels than the nonanxious group, which the authors interpret as elevated muscular tonus in the anxious group.
• There were no group differences in EMG skewness between GAD and nonanxious participants.
• During the laboratory stressor, the GAD group showed a significant reduction in frontalis EMG variability (less moment-to-moment change in forehead muscle activity).
• During the stressor, gastrocnemius EMG for both groups increased in mean level and in variability, and decreased in skewness.
• The authors note that the gastrocnemius showed clear stress reactivity, while the frontalis did not, and they suggest that this EMG analysis approach may help distinguish features of anxiety and other emotional disorders.
• The study tested only women in a laboratory setting, so the findings apply to the studied sample and may not generalize to men or to real-world situations.

Abstract

The purpose of this study was to investigate the amplitude characteristics of frontalis and gastrocnemius electromyographic (EMG) activity in clinically anxious and nonanxious populations. Eighteen women with generalized anxiety disorder (GAD) and 19 nonanxious women were compared during baseline, laboratory stressor, and recovery conditions. EMG mean levels were greater for the GAD group, but there were no group differences in EMG skewness. During the stressor the GAD group had a significant reduction in frontalis EMG variability. Gastrocnemius muscle activity for both groups during the stressor condition increased in mean levels and variability while decreasing in skewness. These results indicate that clinically anxious individuals have elevated muscular tonus and have reduced variability in frontalis activity during stressful tasks. Also, the gastrocnemius muscle exhibited a stressor reactivity, whereas the frontalis did not. This study presents an approach to EMG analysis that could be useful in distinguishing unique features of anxiety as well as other emotional disorders.

Topics

Anxiety, Depression, Psychometrics, Treatment, Cognitive Processes Obsessive-Compulsive Spectrum Disorders Psychosomatic Disorders and Their Treatments

Categories

Experimental and Cognitive Psychology Psychology Social Sciences

Tags

Anatomy Anxiety Clinical psychology Electromyography Forehead Frontalis muscle Gastrocnemius muscle Generalized anxiety disorder Internal medicine Medicine Muscle tension Physical medicine and rehabilitation Psychiatry Psychology Skeletal muscle Stressor