Background: Social comparison feedback is often used in physical activity interventions but the optimal design of feedback is unknown. Methods: This 4-arm, randomized trial consisted of a 13-week intervention period and 13-week follow-up period. During the intervention, 4-person teams were entered into a weekly lottery valued at about $1.40/day and contingent on the team averaging ≥7000 steps per day. Social comparison feedback on performance was delivered weekly for 26 weeks, and varied by reference point (50th vs 75th percentile) and forgiveness in use of activity data (all 7 d or best 5 of 7 d). The primary outcome was the mean proportion of participant-days achieving the 7000-step goal. Results: During the intervention period, the unadjusted mean proportion of participant-days that the goal was achieved was 0.47 (95% confidence interval [CI]: 0.38 to 0.56) in the 50th percentile arm, 0.38 (95% CI: 0.30 to 0.37) in the 75th percentile arm, 0.40 (95% CI: 0.31 to 0.49) in the 50th percentile with forgiveness arm, and 0.47 (95% CI: 0.38 to 0.55) in the 75th percentile with forgiveness arm. In adjusted models during the intervention and follow-up periods, there were no significant differences between arms. Conclusions: Changing social comparison feedback did not impact physical activity.
Randomized trial of amino acid mixture combined with physical activity promotion for abdominal fat reduction in overweight adults
