Abstract
BACKGROUND: The Bari-Active trial found that a physical activity (PA) intervention (PAI), versus standard presurgical care control (SC), produced significant increases in daily bout-related moderate-to-vigorous PA (MVPA, in≥10-min bouts) preoperatively. The present study examined whether PAI also produces superior improvements in psychological and/or motivational processes that may be important for PA adoption. OBJECTIVES: Compare PAI and SC on baseline to postintervention changes in PA-related enjoyment, self-efficacy, and motivations, and examine whether greater bout-related MVPA changes are associated with greater improvements in these variables. SETTING: University hospital, United States. METHODS: Participants (87% female; body mass index = 45.0±6.5 kg/m(2)) were randomly assigned to 6 weeks of PAI (n = 40) or SC (n = 35). PAI received weekly counseling sessions to increase daily walking exercise. At baseline and postintervention, both groups completed 7-day objective PA monitoring and questionnaires to evaluate changes in bout-related MVPA and PA enjoyment, self-efficacy, and motivation. RESULTS: Retention was 84% at postintervention. Intent-to-treat analyses showed that PAI on average reported more favorable changes than SC in PA enjoyment, self-efficacy, amotivation (i.e., lack of PA motivation), and identified and intrinsic regulations (i.e., more autonomous PA motivations; P<.01). In PAI completers (n = 33), changes in bout-related MVPA and psychological/motivational variables were unrelated. CONCLUSION: PAI produced greater improvements in PA-related enjoyment, self-efficacy, and motivations than SC. The lack of association between objectively measured PA changes and psychological/motivational processes highlights the need for future research to identify which processes are most important for PA adoption and maintenance in bariatric surgery patients, and to determine whether the method used to measure PA affects the pattern of association.