MacMillan et al. BMC Public Health 2011, 11:120 http://www.biomedcentral.com/1471-2458/11/120 walking intervention for older adults (West End Walkers 65+), submitted). These steps were taken to strengthen the robustness of the pilot, to enhance the study protocol for a potential larger trial and enhance the generalisabil- ity of learning for general practice from both of these research stages. To summarise, this study was designed to fill several research gaps in the literature. This study will explore the efficacy of a walking intervention (already shown to suc- cessfully increase walking in young to middle-aged adults [17]) in a randomised controlled trial with an older adult population in the UK and using an objective measure- ment of physical activity. The efficacy of the intervention on areas of health important to older adults will also be assessed using specific questionnaires shown to be valid and reliable measures in adult groups. The appropriate- ness of the physical activity recommendations and the walking intervention for older adults will also be explored. In addition this study will examine the feasibil- ity of delivering the walking intervention in a primary care setting (general practice) to provide a practical solu- tion to increasing physical activity levels of older adults, facilitating future implementation via this setting. The study will also look at the feasibility of delivering the walking intervention by a practice nurse (a more likely delivery mode in the UK than via general practitioners who have greater time constraints). Older adults were specifically targeted in this study due to the low propor- tion of Scottish older adults that currently meet the phy- sical activity recommendations [3]. Participants were recruited via a general practice as a means of accessing older adults, due to the high proportion of older adults that attend their general practice in Scotland [13]. Aim This paper provides details of the rationale and study design (including information on the outcome measures assessed and recruitment process). The WEW65+ study aims to examine the delivery of a pedometer-based graduated walking programme in combination with phy- sical activity consultations, through a primary care set- ting (general practice), to older Scottish adults who are currently not meeting the physical activity recommenda- tions. The feasibility issues are: recruitment of partici- pants into the study (who is targeted versus who is actually recruited) and delivery of the intervention via a primary care setting (general practice); delivery of the intervention by a practice nurse; practicality of adminis- tering the outcome measures; and whether the interven- tion is acceptable and enjoyable for an older adult population in a real-life setting. Determining the efficacy of the intervention in an older adult population (≥65 years) is also a pilot element of this study as the intervention has previously been shown to successfully Page 4 of 12 increase walking participation in adults aged 18-65 years [17] but has not been tested in older adults. For the pilot component of this study, efficacy of the interven- tion will be evaluated by looking at the effect of the intervention on step counts (primary outcome), activity patterns and sedentary behaviour, mood, quality of life, perceived motor-efficacy and loneliness (secondary out- comes). Another pilot element of this study will be to assess if all components of the study can be implemen- ted simultaneously and work together to have an effect on physical activity before planning a full trial. The main research questions are:- Is the recruitment and retention strategy successful? Is the intervention acceptable, appropriate, accessi- ble and useable for this group? What is the efficacy of the intervention on out- come measures? Are the outcome measures acceptable for this group? Methods/Design Ethical Approval All procedures were approved by the NHS Greater Glas- gow and Clyde and University of Strathclyde Ethics Committees and were carried out in accordance with the Declaration of Helsinki. Written informed consent was obtained from all participants. Power Calculation For the pilot element of this study, sample size was esti- mated based on the primary outcome measure, ped- ometer steps/day. Based on findings from previous work conducted by this research team a conservative estimate of the potential effect in this study was a mean increase of 2,000 steps/day [17]. From prior research [44,45], a conservative estimate of the standard deviation for steps/ day in older adults is 3,000 steps. This corresponds to an effect size of D = .67 [46]. Additionally, pedometer counts from older adults have been shown to be highly reliable [44], thus a high correlation between baseline and post-intervention data can be expected. Using the Power and Precision software, sample size for a Repeated Measures ANOVA was calculated for D = .67, a = .05, an inter-trial correlation of r = .60, and a desired power of b = .80. This yielded a sample size of 16 participants per group. Assuming a 30% loss in follow-up, a sample size of 46 (23 per group) was agreed as the target. Recruitment process Recruitment commenced in August 2009. Medical records were screened for contraindications to physical