Interventions to Increase Physical Activity Among Healthy Adults: Meta-Analysis of Outcomes

Objectives. We conducted a meta-analysis summarizing the effects of interventions designed to increase physical activity among healthy adults. Methods. Our comprehensive searches located 358 reports eligible for inclusion. We used random-effects analyses to synthesize data, and we used meta-analytic analogues of regression and analysis of variance to examine potential moderator variables. We also explored moderator variable robustness and publication bias. Results. We computed meta-analytic results from studies comprising 99011 participants. The overall mean effect size for comparisons of treatment groups versus control groups was 0.19 (higher mean for treatment participants than for control participants). This effect size is consistent with a mean difference of 496 ambulatory steps per day between treatment and control participants. Exploratory moderator analyses suggested that the characteristics of the most effective interventions were behavioral interventions instead of cognitive interventions, face-to-face delivery versus mediated interventions (e.g., via telephone or mail), and targeting individuals instead of communities. Participant characteristics were unrelated to physical activity effect sizes. Substantial between-studies heterogeneity remained beyond individual moderators. Conclusions. Interventions designed to increase physical activity were modestly effective. Interventions to increase activity should emphasize behavioral strategies over cognitive strategies. (Am J Public Health. 2011;101:751-758. doi: 10.2105/AJPH.2010.194381)