The association of acute stress and lower quarter EMG during a single leg balance dexterity task.

Background: There is a well-established connection between psychosocial stress and low back pain, however studies demonstrating a connection between motor control and acute stress are lacking.

Research question: What is the potential interaction of acute stress (the Feigned Annoyance and Frustration Test, or the FAF Test) with lower quarter motor control and stance stability during a standing lower-extremity dexterity task in individuals with and without low back pain?

Methods: This prospective cohort study included 30 individuals with low back pain (15 men and 15 women) with an equal number of sex-matched controls for a total sample of 60 participants. Participants were fitted with surface electromyography sensors over the trunk and lower extremities. The lower extremity dexterity task was performed on 2 in-ground force plates while center of pressure data was collected. Participants were exposed to the FAF Test and the lower extremity dexterity task was repeated.

Results: Stress resulted in decreased muscle activation for muscles of the trunk and gluteals, as well as decreased total excursion and velocity of the center of pressure.

Significance: Acute stress appears to alter trunk control during a standing lower extremity dexterity task, with more pronounced changes apparent in participants with low back pain. These findings provide novel insight into the influence of stress on trunk control and balance stability.