This longitudinal study measured the sustainability of the whole-community project '10,000 Steps' in extension of our previous research on this project's dissemination and implementation process in Flanders [15
]. It contributes additional findings to the limited research on sustainability of community-wide PA programs available in the literature [9
Levels of project continuation among organizations were 50% which was 10% lower than the 60% benchmark reported by a review on empirical sustainability studies of health-related programs [11
]. However, this comparison should be interpreted with caution because the types of programs reviewed varied considerably and may not be directly comparable to '10,000 Steps'. It has been hypothesized that complex interventions, such as whole-community projects, that call for changes in different socio-ecological levels of dynamic systems (i.e. communities) are more difficult to sustain [12
]. Further research on the sustainability of other whole-community projects promoting PA could explore this hypothesis.
Conceptual frameworks argue that sustainability is determined by a combination of factors related to project design, organizational setting, and the broader context [5
]. Findings of the present study support these frameworks and suggest several factors particularly important for increasing the sustainability of whole-community projects like '10,000 Steps'. Reported reasons for project continuation indicate the importance of offering ready-for-use and adaptable interventions to public service organisations including project manuals, materials and websites (project design factors), targeting the organization's superior as a project champion (organizational setting), and providing funding or external support from other stakeholders (broader context). A major reported barrier to project continuation was the preference to switch to another PA project. Next to a lack of project compatibility with the perceived needs of reporting organizations, this finding suggests a need for organizations to have a choice in their decision-making about project implementation. Dearing and colleagues [28
] argue that increasing project choice is a key principle for disseminating proven approaches to PA promotion. A logical recommendation would be to combine sustainability strategies of '10,000 Steps' with strategies that cluster alternative evidence-based programs [28
]. The web portal Cancer Control PLANET (Plan, Link, Act, and Network with Evidence-based Tools) is a practical example of this principle [29
]. Considering external validity indicators in the present study, these were promising, with project continuation rates found to be independent of staff size, type of organization and working context. The global implementation score (58%) remained stable and the majority of project components were continued by more than half of organizations. It is encouraging that partnerships in particular were continued by 75% of organizations as partnerships with other stakeholders are argued to have a positive influence on long-term sustainability of projects [11
]. Three project components (personal contact, street signs and variants, and posters) were continued by less than half of organizations. These same components also had low implementation rates with negative z
-scores in both the current study and the prior dissemination and implementation study. Personal contact with citizens seemed infeasible for a substantial portion of organizations, which is consistent with findings of a smaller scale dissemination study of an evidence-based PA promotion program for the elderly in community organizations [30
]. Mixed reasons, including costs, were listed for non-implementation of street signs or variants, implying the need for alternatives. After similar reasons had been reported in the prior dissemination and implementation study, the Flemish Government initiated an intermediate support structure for '10,000 Steps' on the regional level. This intermediate structure consisted of linkage agents (health promotion services) who developed more workable alternatives such as street banners and flags. However, because planning time for both the intermediate structure and alternative materials was underestimated, availability of these materials was delayed by 1 year. The potential of street banners and flags could therefore not be fully assessed. Production delays of other project materials on the regional level were directly reflected in listed reasons for not continuing the use of posters. Several organizations listed dependency of poster production on the regional level which forced them to continue '10,000 Steps' without posters. This underlines the importance of synchronizing project strategies and change across different levels of a social system to optimize sustainability, as also suggested by Schensul [12
]. When considering the targeted PA domains, it was clear that leisure time was the organizations' preferred context to continue the promotion of '10,000 Steps', followed by transport, household, and work.
Several organizations changed the project focus of '10,000 Steps' and switched between a whole-community approach and a specific target group (e.g. the elderly). This emphasizes that sustainability is a dynamic process and strategies for achieving it ought to adapt to changing contexts and priorities [5
]. In order to facilitate this dynamic process, project manuals should include extensive guidelines for project adaptations that don't jeopardize project fidelity. This includes specific manuals for projects targeting the elderly only, or projects in workplaces. Furthermore, many organizations continuing '10,000 Steps' changed the original campaign image into one that reflected their regional or local identity (e.g. colours, partner logos, and multiple images). As argued by Dearing and colleagues [28
], it is important that projects provide organizations more opportunities to raise their profile and to feel project ownership as a strategy to encourage project sustainability. Furthermore, organizations reported alternatives for less sustainable project components, such as exhibition banners or foot stickers in public places instead of regular posters. This kind of information is useful for formulating guidelines on how to reinforce or replace less sustainable components with alternatives that retain the original function of promoting awareness and knowledge about PA. Future sustainability studies of community-wide PA programs could facilitate the spread of best practices for various settings by documenting adaptations and whether these adaptations retain essential behaviour change elements [7
Institutionalization levels for routines and project saturation indicate that '10,000 Steps' became moderately integrated within the culture of organizations through policies and practice. However, two separate aspects of institutionalization were poorly integrated. Few permanent staff members contributed to project implementation, which could jeopardize sustainability in case of staff turnover. In addition, very few organizations reported formal project evaluation. As evaluation was not explicitly recommended in the initial '10,000 Steps' project findings suggest it is necessary to do so in the future. Wilson and Kurz [31
] argue that lack of evaluation is a significant threat to institutionalization. Without evaluation, the project's potential benefits cannot be monitored, which may reduce relevancy of the project within the organization. In order to facilitate project evaluation and sustainability a combination of measures is recommended. First, Wilson and Kurz [31
] recommend providing organizations with training and practical methods for continuous evaluation and quality improvement, such as the "Plan-Do-Study-Act" framework [32
]. Second, this study also supports Brug and colleagues [33
] who argue the importance of better planning, considerable more funding opportunities for evaluation, and the formation of collaborative centers between public health services and academic experts.
Seven out of twelve organizations reported to have sustained '10,000 Steps' by implementing periodically repeated projects rather than ongoing projects. This implies that project sustainability in organizations can also manifest itself in repeated time cycles rather than on a continuous basis only. This alternative approach to the time dimension of sustainability seems more logical and appropriate for projects like '10,000 Steps' which aim to increase citizens' awareness about PA. For example, project components such as street banners may be disregarded by citizens after years of permanent allocation. Such components may grasp interest of citizens in a more sustainable manner when implemented repeatedly in cycles and as part of a comprehensive intervention [34
]. As discussed previously, it would be recommendable to offer project choice to organizations in public health. This would allow organizations to alternate cycles of '10,000 Steps' with cycles of other evidence-based PA programs. This also implies that projects like '10,000 Steps' would need to innovate regularly (e.g. by anticipating and facilitating adaptations) to sustain high levels of interest in both adopters and citizens. The optimal duration or schedule for project cycles of '10,000 Steps' is probably different for each community context because sustainability is a dynamic process. However, based on the present study it seemed that periodically repeated projects can be feasible when they have a maximum duration of 1 year and are alternated with varying periods of interruption.
In the prior dissemination and implementation study, significant differences in domain-specific self-reported levels of PA were only found for leisure-time PA, with citizens aware of '10,000 Steps' found to have higher levels than those not aware [15
]. No differences were found for intensity-specific self-reported levels of PA at that time. The same comparative analyses for the current sustainability study confirmed maintenance of significantly more leisure time PA in citizens aware of '10,000 Steps'. In addition, in the current study citizens aware of '10,000 Steps' also reported significantly more household-related and moderate intensity PA. Project materials of '10,000 Steps' promoted all PA domains and also the public health guideline of 30 min of moderate to vigorous intensity PA per day, which may have contributed to additional time-delayed effects in favor of citizens aware of '10,000 Steps'. Furthermore, results suggest (although not significant) that citizens that were unaware of '10,000 Steps' had more work-related PA and vigorous intensity PA. The latter finding could indicate higher fitness levels in these citizens. However the testing of fitness levels was beyond the scope of the current study.
Limitations of this study include the use of self-report data and reliance on only one respondent per organization. With more resources these approaches could become more valid by adding objective types of data collection (e.g. on-site observations) and by contacting multiple respondents per organization [11
]. While the sample of organizations was relatively small, which may limit external validity of results, the sample itself appears to be generalizable. In the prior study of '10,000 Steps' [15
] external validity analyses revealed no significant differences between these same organizations and the larger group (n
= 44) of non-adopting organizations on organizational characteristics (e.g., size, type, and context). Moreover, despite their small number, organizations in the current study served substantial populations and could have wide-scale impact on public health. Finally, this study did not address the issue of capacity building and community level changes, which is considered a third indicator of sustainability [3
]. For example, we did not explore if a capacity-building strategy for local staff members influenced the sustainability of '10,000 Steps' or the development of other PA programs. Green [35
] argued that rather than program continuation and institutionalization the most appropriate goal of sustainability may be that practitioners learn new skills and new program approaches.
Strengths of this study include its contribution to a small available literature on the sustainability of community-wide physical activity (PA) programs in general and of '10,000 Steps' in particular. Sustained implementation of project components and adaptations were also assessed. This provided more insights in less sustainable components and its contextual barriers, which may also be relevant for other sustainability research. Reported adaptations provide additional information to potentially improve project sustainability in various and changing contexts.