Are physical activity interventions for healthy inactive adults effective in promoting behavior change and maintenance, and which behavior change techniques are effective? a systematic review and meta-analysis

Background: Physical inactivity and sedentary behavior relate to poor health outcomes independently. Healthy inactive adults are a key target population for prevention. Purpose: This review aimed to evaluate the effectiveness of physical activity and/or sedentary behavior interventions, measured post-intervention (behavior change) and at follow-up (behavior change maintenance), to identify behavior change techniques (BCT) within, and report on fidelity. Methods: A systematic review and meta-analysis of randomised controlled trials, targeting healthy inactive adults, aiming to change physical activity and/or sedentary behavior, with a minimum post-intervention follow-up of 6 months, using 16 databases from 1990. Two reviewers independently coded risk of bias, the TiDieR checklist, and BCTs. Results: Twenty-six studies were included; 16 pooled for meta-analysis. Physical activity interventions were effective at changing behavior (d = .32, 95% CI .16 to .48, n=2346) and maintaining behavior change after 6 months or more (d = .21, 95% CI .12 to .30, n=2190). Sedentary behavior interventions (n=2) were not effective. At post-intervention, physical activity intervention effectiveness was associated with the BCTs ‘Biofeedback’, ‘Demonstration of the behavior’, ‘Behavior practice/rehearsal’, and ‘Graded tasks’. At follow-up, effectiveness was associated with using ‘Action planning’, ‘Instruction on how to perform the behavior’, ‘Prompts/cues’, ‘Behavior practice/rehearsal’, ‘Graded tasks’, and ‘Self-reward’. Fidelity was only documented in one study. Conclusions: Good evidence was found for behavior change maintenance effects in healthy inactive adults, and underlying BCTs. This review provides translational evidence to improve research, intervention design, and service delivery in physical activity interventions, while highlighting the lack of fidelity measurement.