Goal feedback from whom? A physical activity intervention using an N-of-1 RCT.

OBJECTIVE: Adolescents are not meeting the recommended guidelines for physical activity. Social support and self-regulatory skills are two factors known to impact physical activity and sedentary behaviour. The study sought to examine how targeting feedback as part of a self-regulatory process could increase physical activity, and the individual who should be providing the feedback. DESIGN: The study utilised an aggregated N-of-1 RCT which allows for an iterative process of intervention development, and examines variability within participants to answer the question for whom did the intervention work. Ten adolescents (ages 13-18) set a daily physical activity goal. Adolescents received a SMS text message providing feedback on goal attainment daily from a parent, peer, behavioural health specialist; or no text message (control). MAIN OUTCOME MEASURES: A bioharness heart rate monitor assessed heart rate as proxy for goal attainment. Adolescents also self-monitored their physical activity in the Calorie Counter and Diet Tracker by MyFitnessPalTM app (commercially available). RESULTS: Intervention demonstrated a significant effect for 30% of the sample in increasing MVPA (Mincrease = 52 min), with no significant effect on sedentary behaviour. CONCLUSION: A single occasion of text messaging from the right person can produce changes, however, careful consideration should be given to who provides the feedback.

The promise of wearable sensors and ecological momentary assessment measures for dynamical systems modeling in adolescents: a feasibility and acceptability study.

Intervention development can be accelerated by using wearable sensors and ecological momentary assessment (EMA) to study how behaviors change within a person. The purpose of this study was to determine the feasibility and acceptability of a novel, intensive EMA method for assessing physiology, behavior, and psychosocial variables utilizing two objective sensors and a mobile application (app). Adolescents (n = 20) enrolled in a 20-day EMA protocol. Participants wore a physiological monitor and an accelerometer that measured sleep and physical activity and completed four surveys per day on an app. Participants provided approximately 81 % of the expected survey data. Participants were compliant to the wrist-worn accelerometer (75.3 %), which is a feasible measurement of physical activity/sleep (74.1 % complete data). The data capture (47.8 %) and compliance (70.28 %) with the physiological monitor were lower than other study variables. The findings support the use of an intensive assessment protocol to study real-time relationships between biopsychosocial variables and health behaviors.