Helping clients overcome barriers to physical activity: a theory-based approach for mental healthcare providers.

Physical activity is effective for managing mental health conditions, yet a deeper understanding of factors linked with physical activity behaviors among mental health clients is needed. This cross-sectional study aimed to test a theory of planned behavior process model in a large, representative sample of adults in therapy. Participants (N = 478, M = 31.7 years, 44.6% male) completed an online survey including validated measures assessing theory of planned behavior variables (e.g. attitudes, subjective norms, perceived behavioral control, and intentions) and physical activity. The model tested whether attitudes, norms, and perceived behavioral control predicted physical activity frequency indirectly through intentions while controlling for various demographic and mental health variables. Depression, anxiety, stress, loneliness, and body dissatisfaction were also evaluated as moderators. The fully adjusted model fit well (χ2 [282] 725.27, p < .01 RMSEA = .06, CFI = .93). Only perceived behavioral control had a significant bootstrapped indirect effect on physical activity behavior via intentions (b = 13.57, 95% CI: 8.47-21.97). The association between perceived behavioral control and physical activity intention was significantly moderated by body dissatisfaction (b=.08, p=.035), with a stronger effect in participants with high body dissatisfaction. Depression moderated the relationship between attitudes and intentions (b=-.02, p=.011), and body dissatisfaction moderated the relationship between subjective norms and intentions (b=-.05, p=.003). Mental health care providers may use these findings to tailor discussions about physical activity with clients to address individual needs and preferences and help clients develop strategies to overcome physical activity barriers. Improving clients' perceptions of control may improve physical activity intentions and behavior.