Psychophysiological responsivity on a laboratory stress task: methodological implications for a stress-muscle...

Area of Science:

• Physiology
• Musculoskeletal Health
• Pain Research

Background:

• The stress-muscle hyperactivity-pain (SMP) model proposes a link between stress, muscle overactivity, and pain.
• Understanding the physiological responses to stress is crucial for explaining musculoskeletal pain disorders.

Purpose of the Study:

• To test the prediction of the SMP model that physiological arousal occurs during stress compared to rest.
• To investigate muscle hyperactivity in relation to stress in individuals with temporomandibular disorders (TMD).

Main Methods:

• 31 subjects performed a reaction time task under controlled laboratory conditions.
• Psychophysiological variables, including masseter electromyography (EMG), were monitored during stress and rest periods.
• Analyses focused on different time intervals of EMG data, comparing TMD patients with symptom-free individuals.

Main Results:

• Small, statistically significant differences in masseter EMG supported the SMP model when averaged over 12-second to 2-minute intervals.
• EMG analysis over longer blocks (10-18 minutes) did not support the SMP model, highlighting the importance of analysis duration.
• Masseter EMG increased during rest intervals following stress tasks, suggesting a potential need to modify the SMP model.

Conclusions:

• The study provides partial support for the SMP model, particularly regarding muscle activity during stress.
• The findings underscore the critical role of selecting appropriate time intervals for psychophysiological data analysis.
• A modification to the SMP model may be required to account for sustained muscle activity during post-stress recovery periods.