This early-phase trial will test intervention strategies to influence affective mechanisms underlying physical activity and determine whether changes in those mechanisms result in change in physical activity behavior among inactive adults who are overweight or obese.
This ORBIT model phase 1 trial will examine whether affective mechanisms (1) can be experimentally manipulated in real-world settings; and (2) mediate the relationship between interventions and physical activity behavior. A novel physical activity intervention will be optimized by efficiently disentangling the effects of its core component and two enhancement components on affective mechanisms associated with physical activity engagement.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
TRIPLE
Enrollment
280
On days participants plan to exercise, they engage in two daily goal sessions (morning and evening). Morning sessions provide an activity goal for the day and ask the participant to create a plan, anticipate barriers, and brainstorm solutions for achieving this goal. The affect-based goal condition asks participants to engage in either (1) a type (50% of daily goals) or (2) a context (50% of daily goals) of physical activity that allows them to experience positive affect. Goals focused on context are randomly generated to suggest that the participant performs activity (1) in a place; (2) in a social situation; or (3) while listening to something that makes them feel good. The intensity-based goal condition asks participants to maintain a certain target heart rate range during physical activity. Starting heart rate reflects the approximate age-adjusted heart rate max, with goals progressively increasing from 55% to 70% heart rate max.
TYPE/CONTEXT augments intervention effects by providing tailored recommendations for activity types and contexts that satisfy personally-important psychological needs as rated by each participant at baseline. Ratings from a crowdsourced panel of adults on Amazon Mechanical Turk will be used to determine the potential for specific activity types and contexts to satisfy psychological needs; our tailoring algorithm will then recommend the corresponding activity type or context while accounting for reported constraints (e.g., ability, access). These details will be incorporated into a tailored recommendation provided to participants each Sunday as they make activity plans for the upcoming week. Specifically, the program will randomly select either type or context (i.e., location, audio, social) recommendations and will rotate every two weeks. For TYPE, participants' top 3 activity types are recommended; for CONTEXT, participants' top 3 activity contexts are recommended.
University of Southern California
Los Angeles, California, United States
RECRUITINGPhysical Activity: Step Count
Daily steps will be calculated from minute-level accelerometer data. Fitbit Versa 3 smartwatches with internal accelerometers are worn for the duration of the study period, except while bathing or charging. Only days with sufficient wear time (defined as ≥ 10-hours of valid data, where no more than 20-minutes per hour has a consecutive step count of zero) are used for analysis.
Time frame: Daily total for weeks 1-19
Physical Activity: Minutes
Daily minutes of light, moderate, and vigorous physical activity will be calculated from minute-level accelerometer data. Fitbit Versa 3 smartwatches with internal accelerometers are worn for the duration of the study period, except while bathing or charging. Only days with sufficient wear time (defined as ≥ 10-hours of valid data, where no more than 20-minutes per hour has a consecutive step count of zero) are used for analysis.
Time frame: Daily total for weeks 1-19
Affective Response
Event-contingent ecological momentary assessment (EMA) check-ins sent to the smartwatch during physical activity measure affective response. Event-contingent EMA are triggered when Fitbit sensors detect physical activity via moving average heart rate. A ≥30-minute buffer separates the first and second EMA during a single physical activity bout. A maximum of two event-contingent EMA will be sent within any given 60-minute period. Participants are asked to safely pause their activity to answer seven items about their affective response using a 5-point bipolar Likert Scale. Five items (Energetic-Fatigued, Happy-Discouraged, Relaxed-Tense, Excited-Bored, Satisfied-Frustrated) are drawn from Russell's Circumplex Model of Affect; one (Good-Bad) represents core affective valence; and one (Proud-Embarrassed) represents self-conscious emotion.
Time frame: Max 2 per 60-min physical activity period during weeks 2-9 and weeks 12-19
Affectively-Charged Motivations
Affectively-charged motivations for physical activity are measured during the morning goal session via REDCap. A text message alerts participants to complete the morning goal session on their smartphone. A single item from the Attraction-Antipathy subscale of the AFFEXX measures affectively-charged motivation by asking, "How do you feel about doing physical activity today?". Participants select a response using a Visual Analogue Scale ranging from 0 (Dread) to 100 (Excited).
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SAVOR implements a brief savoring exercise on the smartphone that takes place either after the planned physical activity session or during the evening goal session (after the self-monitoring module). Participants will respond to questions that are intended to enhance and prolong positive experiences during physical activity. To trigger attentional deployment, a common savoring strategy that involves intensifying experiences by focusing on them, participants will answer three open-ended prompts. These prompts are drawn from a prompt pool with slightly varied wording to promote a sense of novelty. Savoring prompts will rotate daily and have a day lag built in every week (i.e., Week 1 Monday Savoring Prompts are Week 2 Tuesday Savoring Prompts).
Time frame: Up to once daily for weeks 2-9 and weeks 12-19
Anticipated Affect
Anticipated affect is measured during the morning goal session via REDCap. A text message alerts participants to complete the morning goal session on their smartphone. A single item asks, "How do you expect to feel during physical activity today?". Participants select a response using a Visual Analogue Scale ranging from 0 (Miserable) to 100 (Thrilled).
Time frame: Up to once daily for weeks 2-9 and weeks 12-19