Confident Moves Intervention Efficacy Trial: Obesity Care Settings

ActiGraph wGT3X-BT

Device-measured physical activity (PA) will be assessed at W1 and W3 using the ActiGraph wGT3X-BT (Pensacola, FL, USA), a tri-axial research-grade accelerometer. Devices will collect data at 30 Hz and be reintegrated into 60-s epochs. Non-wear will be defined as ≥90 consecutive minutes of zero counts, allowing ≤2 min of nonzero counts if surrounded by ≥30 min of zeros. Data will be considered valid if participants have ≥3 days with ≥10 h/day of wear, no device malfunction, and consistency with logs. Moderate-to-vigorous PA (MVPA) will be defined as ≥3,941 counts/min using wrist-specific vector magnitude cut-points validated in free-living adults.

Whole Person Health Index (WPHI) scale

The Whole Person Health Index (WPHI) will be measured at W1 and W3 using a 9-item self-reported scale developed by the National Center for Complementary and Integrative Health, in collaboration with the Centers for Disease Control and Prevention. The WPHI assesses overall health across physical, psychological, and social domains, reflecting a whole person health framework beyond disease-specific outcomes. Items assess general health, quality of life, social/family connections, diet, physical activity, stress management, sleep, meaning/purpose, and ability to manage health, rated on a 5-point Likert scale (1=poor to 5=excellent). The WPHI is validated and used in observational and clinical studies, including the 2025 National Health Interview Survey. Total scores range from 9 to 45, with higher scores indicating better health outcomes.

Physical Activity Self-Efficacy (PASE) scale

Physical Activity Self-Efficacy (PASE) will be assessed at W1 and W2 using a 36-item self-reported scale measuring confidence in achieving recommended weekly physical activity (PA). PASE evaluates self-efficacy across four domains: occupational, transport, domestic, and leisure PA. Occupational and leisure domains include moderate- and vigorous-intensity activities, whereas transport and domestic domains include moderate-intensity activities only. Items are rated on a 5-point scale (0 = no confidence to 4 = complete confidence), consistent with standard self-efficacy measures. Total scores range from 0 to 144, with higher scores indicating greater PA self-efficacy.

Self-Efficacy to Regulate Physical Activity (SERPA) scale

Self-efficacy to regulate physical activity (SERPA) will be measured at W1 and W2 using a 13-item version of the SERPA scale. This scale will assess participants' confidence in their ability to overcome barriers to sustaining weekly PA. Previous measurement studies of the SERPA scale indicate a two-factor structure reflecting different types of barriers to PA. Items are rated on a five-point self-efficacy scale (0 = no confidence to 4 = complete confidence). Total scores range from 0 to 52, with higher scores indicating better outcomes.

Self-Efficacy for Whole Person Health (SE-WPH) scale

Self-Efficacy for Whole Person Health (SE-WPH) will be measured at W1 and W2 using a newly developed 9-item self-reported scale. The SE-WPH assesses confidence in engaging in and sustaining behaviors that support whole person health across physical, psychological, and social domains, aligned with the Whole Person Health Index (WPHI). Items reflect key areas including overall health and quality of life, social connections, health behaviors (diet, physical activity, sleep, stress), and health self-management. Items are rated on a 5-point scale (0 = no confidence to 4 = complete confidence). Psychometric evaluation (reliability and validity) will be conducted prior to hypothesis testing. Total scores range from 0 to 36, with higher scores indicating greater self-efficacy.

Self-Efficacy to Engage (SE-E) scale

Self-Efficacy to Engage (SE-E) will be measured at W2 among participants in the CM group upon access to the intervention, using a previously developed 7-item self-reported scale. The SE-E assesses confidence in engaging with the online intervention and is conceptually aligned with subjective engagement. An example item is: "How confident are you in your current ability to pay close attention when engaging with this online intervention?" Items are rated on a 5-point scale (0 = no confidence to 4 = complete confidence). Although previously developed, the scale was only used in a feasibility trial; thus, reliability and validity will be evaluated prior to hypothesis testing. Total scores range from 0 to 28, with higher scores indicating greater engagement self-efficacy.