Comparing 3 Goal-Setting Techniques to Promote Adherence to National Physical Activity Guidelines in Midlife Adults: Feasibility Trial of a Mechanistic Study Design.

Background: Engaging in regular aerobic physical activity (PA) during midlife is associated with reduced risk for Alzheimer disease and related dementias. Yet, most midlife adults fail to meet national PA guidelines. Goal setting is a commonly used behavior change technique to increase PA, but limited empirical evidence exists regarding whether certain types of goal setting are more effective than others. This study served as an initial step toward understanding how different goal-setting strategies may enhance PA and promote adherence to national PA guidelines among insufficiently active midlife adults with obesity. Objective: This study aimed to establish the feasibility and acceptability of a 4-arm mechanistic trial design comparing 3 different PA goal-setting techniques with a non-goal-setting comparison condition. Methods: This study was a 6-month stage IA mechanistic trial (based on National Institute on Aging's Stage Model) that randomized insufficiently active midlife adults with obesity to 1 of 4 study groups: (1) Static Goal-Setting Group (weekly moderate to vigorous physical activity [MVPA] goal of 150 minutes), (2) Self-Selected Goal-Setting Group (participants self-selected a weekly MVPA goal), (3) Incremental Goal-Setting Group (weekly MVPA goal 20% greater than the previous week), and (4) Non-Goal-Setting Comparison Group (encouraged to increase MVPA without specific reference to a weekly goal). All participants (n=24) received a standardized, Social Cognitive Theory-based PA promotion intervention, which consisted of structured action planning sessions and a Fitbit activity monitor for self-monitoring of MVPA. The only difference across study groups was the goal-setting technique implemented. Primary outcomes included feasibility of study implementation, as assessed by recruitment, retention, and engagement rates; the ability to deliver the intervention as planned and collect outcomes necessary for evaluating the effects of different goal-setting techniques in a subsequent larger-scale trial; and participant acceptability of the intervention, as assessed by participant perceptions of and satisfaction with the intervention. Results: The sample (n=24; mean age 54.1, SD 5.8 years; mean BMI 36.3, SD 5.0 kg/m2) was recruited in approximately 4 months, equating to an enrollment rate of 6 participants per month. Retention at 6 months was 87.5% (21/24). Participants completing the intervention attended 85.9% of action planning sessions and wore the Fitbit for >10 hours per day on 87.1% of intervention days. Data collection rates for outcome measures ranged from 96% to 100%. Most participants expressed satisfaction with the intervention, with 86% (18/21) reporting gaining knowledge about PA and 90% (19/21) reporting that they would recommend the study to a friend. Conclusions: The next step in this research is to build on these findings by conducting a larger-scale phase 1B proof-of-concept trial to examine the preliminary effects of the goal-setting techniques for increasing MVPA and promoting adherence to national aerobic PA guidelines.