Abstract
IntroductionRecruiting participants into research trials is essential for the advancement of scientific knowledge that depends on clinical research studies. For the field of exercise and physical activity, there is an added difficulty in recruiting participants because participants must be willing to participate in an intervention that requires a significant commitment of both time and physical effort. Therefore, we have planned a systematic review to analyse how methodological factors, intervention characteristics and participant demographics impact recruitment rates in specific populations. This information will help researchers improve the design and recruitment approach in future studies.Methods and analysisA mixed methods systematic review will be performed on studies that implement physical activity interventions and present data on participant recruitment. We plan on searching the Pubmed, Cumulative Index to Nursing and Allied Health Literature and Online Resource for Recruitment research in Clinical Trials databases for potentially eligible articles from database inception through 10 February 2017. A standardised approach will be used to identify studies through a review of titles, abstracts and reference lists. The process for each eligible study is to determine their eligibility, extract data from eligible studies and rate each eligible study’s methodological quality. Exploratory multivariate regression models will be used to determine the effects of methodological factors, intervention characteristics and participant demographics on the recruitment variables of interest.Ethics and disseminationBecause all of the data used in this systematic review has been published, this review does not require ethical approval. The results of this review will be disseminated through peer-reviewed publication as well as through conference presentations.PROSPERO registration number CRD42017057284.