An Exploration of the Commonalities and Unique Associations of Common Health Behavior Theories for Predicting Physical Activity among Individuals Living with Severe Mental Illness

Individuals living with severe mental illness (SMI) experience extremely high rates of secondary health conditions and premature mortality, at least partially attributable to high levels of sedentary lifestyles. The purpose of this study was to evaluate the commonalities and unique associations of social-cognitive theory, self-determination theory, and the theory of planned behavior for predicting physical activity participation for individuals living with SMI. Sixty individuals with SMI were recruited from an assertive community treatment (ACT) program in a mid-western city. Each participant completed a questionnaire focusing on levels of physical activity and constructs described in each health behavior theory. Simultaneous regression analyses were used to explore the phenomena of interest. Results indicated that aspects of each theory may be useful for describing the physical activity behaviors of this group, particularly people with SMI's expec-tations about the outcomes of physical activity participation. Information about the clinical and research implications are provided as well.