Evaluating Mechanisms of Action of Adaptive Goal-Setting for Physical Activity
Condition: Motivation; Physical Activity Promotion; Behavior Change; Mobile Health
Study type: Interventional

Summary: 
      Behavior modification programs hold promise for increasing levels of physical activity (PA)
      for individuals who are insufficiently active. However, existing interventions, which
      typically prescribe uniform PA goals across participants, are limited by their insensitivity
      to changing individual needs and circumstances over time. An alternative approach is to
      continuously adjust goal difficulty to match fluctuations in individual performance, or
      adaptive goal-setting (AGS), which evidence suggests may more effective for increasing PA
      than non-adaptive approaches. Still, no prior studies have examined the psychological
      mechanisms targeted by AGS, which limits the ability to further refine and disseminate this
      technique. In this exploratory study, several candidate mechanisms of AGS (expectancy beliefs
      about goals, perceived value of goals, affective appraisal of goals, implicit attitudes
      towards exercise) will be examined. Adult participants interested in increasing their level
      of physical activity (N = 36) will be randomized to receive 6 weeks of either adaptive
      goal-setting (AGS) or non-adaptive, static goal-setting (SGS) as part of a remote,
      low-intensity PA intervention. The primary aim of the study will be to evaluate the
      hypothesis that AGS, as compared to SGS, results in greater increases over time to four
      hypothesized psychological mechanisms. The secondary aim will be to evaluate whether
      post-intervention increases to any among these three mechanisms mediate the relationship
      between intervention type (AGS vs. SGS) and increases to PA over the course of the
      intervention.
    

Detailed description: 
      Interested participants will schedule and complete a phone screen with a researcher to
      determine eligibility, and if deemed eligible, will complete an initial hour-long baseline
      assessment with a member of the study team. The baseline assessment will be conducted over
      video call using the secure, easy-to-use and HIPAA-compliant Zoom service hosted by Drexel
      University. During the baseline assessment, the assessor will electronically obtain the
      participant's informed consent to participate in the study, guide the participant on using a
      mobile phone application to track their daily steps (Google Fit), verbally provide
      participants with psychoeducational content on safely increasing their physical activity, and
      administer a psychological task (Implicit Association Test) as well as questionnaires
      (Demographics; Physical Activity Enjoyment Scale; Treatment Self-Regulation Questionnaire;
      Self-Efficacy for Exercise Scale). Immediately following the assessment, participants will be
      randomized to receive one of two possible remote physical activity interventions: adaptive
      goal-setting (AGS) or static goal-setting (SGS). Randomization will follow a stratified
      procedure based on age (cutoff point = 45 years), and permuted block randomization will be
      used within strata to assign individuals to an intervention condition (AGS or SGS). Both
      interventions will be preceded by a 10-day baseline "run-in" period during which participants
      will be asked to record their activity but will not receive any daily step goals. In
      addition, in both interventions, a brief (10-minute) mid-study (3-week) check-in call will be
      conducted with each participant by a member of the study team to encourage continued
      compliance with step goals and problem-solve any barriers to increasing physical activity.
      Participants will also complete a brief survey once each week over the course of the
      intervention period. At the conclusion of the intervention period, participants will complete
      several post-intervention questionnaires/tasks and will then be compensated for their
      participation.

      Participants in the adaptive goal-setting condition will begin receiving a new step goal each
      day over text message (SMS) following the baseline run-in period (starting Week 2). These
      messages will continue to be delivered each day for the entire duration of the 6-week
      intervention period (through Week 8), and will contain information about the participant's
      daily-assigned step goal as well as their number of steps on the previous day in reference to
      their previous day's goal. Goals will be calculated using a 60th percentile method
      (consistent with prior research on adaptive goal-setting), such that each day's goal will be
      set to the 60th percentile value of the last 9 days of available step data for that
      participant. Goals will be calculated by an algorithm stored on a remote database that
      automatically extracts user data from the Google Fit cloud server (Google Fitness Store). The
      database will store daily steps data for each participant, use these data to calculate new
      daily step goals and transmit them over SMS using a commercial cloud communications platform.
      The maximum steps goal permitted by the algorithm will be 20,000 steps/day, to ensure that
      goals remain within an attainable range for most individuals. Participants in the static
      goal-setting condition will receive the same exact step goal each day (10,000 steps),
      consistent with prior research, and will receive daily text message updates providing a
      summary of their previous day's steps and encouraging them to reach their 10,000-step goal
      for that day.
    

Intervention name(s): Remotely-delivered physical activity promotion
Intervention type(s): Behavioral
Intervention description(s): Over video-call, participants will receive educational content on safely increasing their levels of physical activity (e.g., selecting an appropriate form of exercise, minimizing health risks, the importance of planning), will receive daily text messages (see arm descriptions) for six weeks and complete a 10-15 minute check-in call at the 3-week point of the intervention to assess compliance with daily step goals as well as to help problem-solve barriers to compliance.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Half of participants will be randomized to receive text message-delivered adaptive goal-setting (goals change each day) for 6 weeks, and half will receive static goal-setting (goals are fixed) for 6 weeks.
Masking: Double (Participant, Investigator)
Primary purpose: Treatment
Keywords: Physical Activity; Goal-Setting; Adaptive Interventions; Health-Related Behavior Change