(PS1-17) Does Motivational Intervention for Physical Activity Decrease Attrition in Sedentary Adults Starting an Exercise Program? A Survival Analysis

Regular physical activity consistent with public health guidelines has many significant mental and physical health benefits like reduced risk for disease, lower stress, and higher energy levels.  Yet, per the Centers for Disease Control and Prevention, only 24.2% of US adults currently meet the public health guidelines for physical activity and 25.3% are physically inactive.  Thus, interventions for physical activity are needed to increase participation in exercise consistent with public health guidelines.  However, the rate of attrition in exercise interventions is approximately 25-50%.  Thus, many who start an exercise program do not experience its many benefits. Prior work has found that extrinsic motivation may be important for initiating exercise, yet intrinsic motivation is an important component for sustaining exercise. This project is a secondary analysis of attrition from a randomized clinical trial testing an exercise intervention that integrated motivational interviewing and contingency management (MI+CM) in sedentary, non-treatment seeking individuals with alcohol use disorder (AUD).  Motivational interviewing seeks to increase intrinsic motivation to exercise while contingency management provides tangible reinforcers (i.e., gift cards) for completing weekly exercise activities. Participants (N=60) were randomly assigned to receive a 16-week MI+CM intervention and a gym membership or a gym membership only. Exercise behavior was assessed via Timeline Followback at the 16-week post-treatment follow-up and attrition was defined as one or more consecutive weeks in which an individual did not exercise at least three times per week, with the exception one caveat. If a participant had 3 bouts of exercise in the week before and after a week at least one episode of exercise they were not considered to have dropped out (i.e., attrition).  We hypothesized that attrition was less likely to occur for participants receiving MI+CM compared with participants who only received a gym membership over a 16-week period. Cox regression survival analysis revealed participants who received MI+CM (n=30) were 0.33 times less likely to be censored than gym membership only participants (OR = 0.33; 95% CI 0.17 -0.64). On average, participants in the MI+CM condition engaged in physical activity for 9.4 consecutive weeks, compared to gym membership only participants who exercised on average 2.3 consecutive weeks before attrition (F (1,58) = 26.02, p < 0.01). This finding demonstrates that motivational interviewing combined with contingency management may be effective in increasing physical activity adherence in sedentary individuals by promoting both intrinsic and extrinsic motivation to exercise.