Evaluating Motivational Interviewing and Habit Formation to Enhance the Effect of Activity Trackers on Healthy Adults' Activity Levels: A Randomized Intervention

The objective for this pilot study is to determine the efficacy of the Fitbit Charge wearable fitness monitor alone or in combination with additional behavior change strategies for increasing physical activity in inactive adults. A secondary objective is to assess the influence of psychosocial factors (e.g. self-efficacy, self-regulation, habit formation) on the effectiveness of this type of behavior change intervention. The central hypothesis is that use of the Fitbit will increase physical activity from baseline and that adding additional strategies will enhance this effect. This hypothesis is based on previous research demonstrating that continuous self- monitoring (using wearable technology) is effective in promotion of weight-loss in overweight and obese adults. This objective will be addressed through pursuing the following specific aims.

Aim 1: To determine the efficacy of using the Fitbit to increase physical activity behaviors and improve health markers in inactive adults. The working hypothesis is that wearing a Fitbit for 3 months will increase physical activity and improve health markers from baseline to follow-up in inactive adults.

Aim 2: To compare the efficacy of the Fitbit alone to the Fitbit in combination with behavior change strategies for increasing physical activity and improving psychosocial factors in inactive adults. The working hypothesis is that using the Fitbit along with behavior change strategies will lead to greater improvements in physical activity and psychosocial factors (self- motivation, self-regulation, self-efficacy, and social support) than using the Fitbit alone.

Aim 3: To assess the influence of individual differences in psychosocial variables on changes in physical activity over the intervention. The working hypothesis is that higher levels of self- motivation, self-regulation, self-efficacy, and social support at baseline will be predictive of greater improvements in physical activity over the intervention, regardless of group assignment.