Given the benefits of physical activity to overall health and well-being, high population levels of inactivity remain of concern, in particular in vulnerable groups such as older adults or those experiencing socioeconomic disadvantage [1, 2]. Community-based programs represent a promising approach for engaging large numbers of people in the settings in which they live [3]. Walking is an activity involving low cost, risk of injury, and skill requirements. Group-based walking programs have been shown to be effective in increasing physical activity [4, 5] and improving health [6]. However, recruitment into such programs, particularly from high-risk groups, is challenging [7], and low retention is often problematic [8, 9]. Little is known about reach, retention rates, participant characteristics, or successful implementation elements of walking programs. Evaluations of ‘real-world’ large-scale physical activity programs in the community are also scarce, and have been highlighted as a priority [5]. Evidence of elements of successful walking group programs would inform future community-based physical activity programs with potential broad and equitable reach and impact.

Heart Foundation Walking (http://walking.heartfoundation.org.au/) is a voluntary group-based community walking program rolled out across Australia in 2007 to facilitate regular physical activity in safe, supportive social environments. There were 1287 registered groups, with varying numbers of participants, as of December 2015. The aim of this study was to examine the reach, retention, sociodemographic and health characteristics, physical activity levels and motivations for joining and remaining in the program.

Heart Foundation Walking is a large, free, community walking program that is unique in its scale and population reach, engaging more than 22,000 registered participants at the time of this evaluation. The program reached and retained a large number of participants, including vulnerable groups. The program had particularly high reach in remote and sparsely populated regions where physical activity facilities and programs are likely to be limited. Retention rates compare favourably to others reported in the scientific literature [20, 21].

The recruitment success of walking groups is often measured by the numbers of participants joining, rather than the reach to those who stand to benefit most [22]. However, walking groups have the potential to widen health inequities if they are not sensitively targeted to reach and cater to the needs of these high-risk groups [7] including women, people who are socioeconomically disadvantaged, older adults, adults who are overweight or obese, and people with, or at risk of, chronic disease, for whom physical activity may be particularly beneficial, but who may face additional health-related barriers to being active [23]. The data show that the Heart Foundation Walking program had good impact in attracting women; older adults; those who are socioeconomically disadvantaged; and those who have one or more chronic diseases or risk factors. The program also attracted a higher than average proportion of participants who live alone. As not all walkers completed surveys, these data are illustrative rather than comprehensive. Given typically lower than average response rates in mail surveys among those who are socioeconomically disadvantaged [24, 25], for example, these data may under-estimate the true reach of the walking program to these individuals.

The repeat cross-sectional design and lack of a control group preclude strong conclusions regarding particular elements that contributed to the favourable reach and retention rates. Nonetheless, the data describe the elements of one successful model, and suggest some features that may be implemented in future programs. These include the sponsorship by a well-known national organisation; targeting regions that may lack services or comparable initiatives; the use of inexpensive wide-reaching recruitment modes; and facilitating social interactions, which appear to be of increasing importance to participants. Given the perceived importance of low-cost walker recognition schemes, communications and special events by the majority of participants, incorporating these elements into future programs would be warranted. Investigating the reasons for continued participation amongst those who did not rate these features as important could also add to our understanding of how future programs might enhance retention. Future programs could also adopt the volunteer model used here, which builds community capacity and reduces costs by engaging and supporting local volunteers as Walk Organisers. Organisers were more physically active but otherwise had comparable characteristics (sociodemographics, BMI) to participants, hence potentially serving as relatable role models. Analyses of retention times suggest that future programs might focus recruitment efforts on traditional media and encouraging existing participants to recruit others.

Typically, participant drop-out rates present a major concern in community health programs. Substantial heterogeneity makes it difficult to directly compare reach and retention rates across different programs. Despite data gaps, existing reports of broadly comparable programs show that 30–76% of people who begin a new exercise program will drop out within 1 year [20, 21, 26]. The greatest attrition typically occurs in the first 3 months (e.g., 36%) [21], and approximately 50% within 6 months [27]. Results from the present study, showing an average 6-month retention of 88%, 1-year retention of 75%, and average participation duration of 2.4 years among Walkers, compare favourably to the rates reported in the limited available literature. Importantly, voluntary attrition was even lower than the rates reported here, which include non-voluntary drop-out (due to illness or death).

A study of a similar community-based program reported by Jancey and colleagues [20] reported a 6 month retention of 65% (i.e. 35% attrition) among adults aged 65–74 years. Unlike Heart Foundation Walking, retention was poorer among those from disadvantaged areas, and those who were obese, or insufficiently active. Program differences that may explain the comparatively higher retention rates of Heart Foundation Walking include the fact that, unlike Jancey et al. [20], Heart Foundation Walking was designed as a long-term program, fostered word-of-mouth recruitment, and fostered community engagement via recruitment and ongoing investment in volunteers.

Around 70% of Walkers and 80% of Organisers were meeting physical activity recommendations. The most recent population prevalence data suggest that only 43% of Australian adults are meeting recommendations [2]. Notably, it was not possible to determine whether Heart Foundation Walking contributed to these high levels of physical activity or whether the program attracted participants who were more active. However, a previous evaluation of a state-based program suggested that participation for 12 months increased both walking and total physical activity, particularly among initially inactive participants [28].

The data presented suggest that the reasons participants joined Heart Foundation Walking were different from the reasons participants continued with the program. Improving fitness and health appeared to be the most important motivators for joining the program whereas the social aspect was the strongest motivator for continuing. Social engagement may be particularly relevant for walking, as opposed to more vigorous or structured group-based activity such as exercise classes, which typically do not offer the same opportunities to talk with other participants during the activity. These data corroborate findings from a meta-analysis showing the most consistent predictor of participation in physical activity programs among socioeconomically disadvantaged women was a social component [29]. This highlights the importance of focusing on building, strengthening and maintaining social networks that support behaviour change [3], particularly given the documented challenges in maintaining behaviour change [5]. In order to attract participants, future walking programs could implement tailored recruitment campaigns that promote benefits to fitness and health as well as opportunities to meet and spend time with others. In light of the finding that few participants were motivated to join as a result of a health professional recommendation, a ‘bring a friend’ initiative might be a more useful promotional approach. Considering the importance of social factors in retaining participants, programs might also consider activities that enhance opportunities for social engagement, such as walks linked with lunches or picnic days. With the increasing proliferation of mobile phone technology, provision of ‘virtual’ support could also be trialled, for example through online challenges and Facebook/social media support groups, to further facilitate social connectedness among participants. Mobile technology could also be used to provide motivational strategies, such as text message congratulations on significant milestones, or ‘we miss you’ messages for those who haven’t walked for some time. The impact and cost-effectiveness of such strategies could be evaluated in future studies.

Capitalising on the unique evaluation of a large, nationwide physical activity program in a real-world setting, this study utilised data from sizeable numbers of respondents over four survey points to explore reach, retention, participant characteristics and motivators for participation in a national walking group program. Notwithstanding these strengths, the study was limited by its reliance on self-report measures collected with tools that have not been tested for validity or reliability among this study population; and use of a repeat cross-sectional design which meant that temporal sequencing could not be determined. We also did not have access to data on frequency of attendance, and did not measure actual health benefits. It is possible that survey respondents were not representative of Heart Foundation Walking participants more generally. In particular the response rate at 2015 was low, potentially reflecting the shift to email-only administration, given typically lower responses to online than paper-based surveys [30].

Walking is a popular activity with health benefits and a low risk of injury that requires little skill or equipment. This study suggests that free group-based walking programs are a promising approach for increasing population levels of physical activity and attracting participants at high risk of inactivity. This study provides a model for such a program, with key elements (summarised in the Box) including backing of a well-known national non-government organisation; support of local government and community health staff; community capacity building via local volunteer Walk Organisers; low-cost and word of mouth promotion; retention strategies including walker recognition schemes, newsletters and annual/special events; and opportunities for social interaction. Though initial motivation factors may include health and fitness, programs should market social aspects as they appear to be an especially important component of group-based walking, particularly for continued participation.