Background: Expectations for psychological responses to exercise are not well characterized, particularly in people at risk for anxiety-related illnesses. Given the substantial evidence for salutary effects of exercise on anxiety symptoms and emerging recognition for expectations as a critical mechanism of placebo/nocebo effects, this study explored the interplay between expectations and physical activity in young adults with and without analogue generalized anxiety disorder.

Methods: Participants (N=470, 23.2±4.8 years, 63% female) completed a physical activity and mood survey, including a 7-day physical activity recall questionnaire, and a 20-item questionnaire designed to measure positive and negative expectations for psychological and perceptual responses to exercise, particularly expectations for symptoms in the generalized anxiety disorder symptom profile. Analogue generalized anxiety disorder status was determined using the Generalized Anxiety Disorder subscale of the Psychiatric Diagnostic Screening Questionnaire.

Results: For select outcomes, expected exercise-induced changes significantly differed according to analogue generalized anxiety disorder (whole-body pain, sleep quality, psychological well-being, stress, relaxation) and active versus inactive (anxious mood, depressed mood, concentration, physical function, psychological well-being, relaxation) status. However, these findings did not survive corrections for multiple comparisons and the magnitude of these differences was small, approximating 0.25 standard deviations. Expectations for anxious (Spearman's ρ=-0.14, p≤0.002) and depressed mood (ρ=-0.15, p≤0.002), and psychological well-being (ρ=0.15, p≤0.001) were significantly associated with higher physical activity levels. Exercise expectations for anxious mood explained a significant, but small (+1.5%, p≤0.03), amount of variance in physical activity.

Conclusions: Expectations for exercise-induced improvements did not significantly differ between young adults based on analogue generalized anxiety disorder or physical activity status.