A cumulative meta-analysis of the effects of individual physical activity interventions targeting healthy adults

Despite a large and increasing evidence base on physical activity (PA) interventions, the high rates of physical inactivity and associated chronic diseases are continuing to increase globally. The purpose of this cumulative meta-analysis was to: investigate the evolution of randomized controlled trial evidence of individual-level PA interventions to asses if new trials are contributing novel evidence to the field. Through a two-staged search process, primary studies examining the effects of interventions targeted at increasing PA within healthy adult populations were pooled and selected from eligible systematic reviews. Cumulative meta-analyses were performed on effect sizes immediately post-intervention (n=62), and for long-term behavior change (≥12-months post-baseline; n=27). Sufficiency and stability of the evidence was assessed through application of pre-published indicators. Meta-analyses suggest overall positive intervention effects on PA. The evidence base for effectiveness immediately post-intervention reached levels of sufficiency and stability in 2007; and for long-term follow-up in 2011. In the time since, intervention effectiveness has not substantially changed, and further trials are unlikely to change the direction and magnitude of effect. Substantial evidence exists demonstrating that PA interventions can modify individual behavior in controlled settings. Researchers are urged to shift focus towards investigating the optimization, implementation, sustainability and cost-effectiveness of interventions.Funding for this study and the work of authors Jean Adams, Esther M F Van Sluijs and Rebecca Love was supported,wholly or in part, by the Centre for Diet and Activity Research(CEDAR), a UKCRC Public Health Research Centre of Excellence (RES-590-28-0002). Within this funding from the British Heart Foundation, Department of Health, Economic and Social Research Council, Medical Research Council and the Wellcome Trust, under the auspices of the UK Clinical Research Collaboration, is gratefully acknowledged.The work of Esther M F van Sluijs was supported by the Medical Research Council (MC_UU_12015/7)