In Australia, consistent with global trends, there is a marked ageing of the population. Those over the age of 65 currently constitute 14.0 % of the population [
1]. By 2061, more than one in five Australians will be over the age of 65, with the fastest rate of growth being among those over 85 [
2].
As the population ages, the increasing incidence of age-related illnesses will have significant economic and social cost implications [
3,
4]. For example, older age is associated with higher body mass index scores [
5,
6], indicating that as the population ages, the economic and health-related costs associated with obesity will escalate. Older people also tend to engage in lower levels of physical activity than other population segments [
7], and are thus in need of programs that can motivate and facilitate their engagement in higher levels of activity. As a result of their greater susceptibility to a wide range of health problems, older people have been recognized as a group requiring particular attention in the design of health promotion and illness prevention programs [
8,
9].
A growing evidence base demonstrates that interventions that focus on physical and social activities can assist in preventing and treating both physical and mental health problems [
10-
14]. There is also an emerging body of knowledge relating to sedentary time as an independent risk factor for physical illness, in particular cardiometabolic diseases [
15-
17]. To date, however, there appears to be no research investigating the effects of being sedentary on mental health, nor the impacts of volunteering on sedentary time. This study will explore the potential for interventions involving volunteer activities to produce positive physical and mental outcomes for older people, thereby contributing to the limited evidence relating to the potential of volunteering as a health intervention.
Volunteering
Volunteering is defined as work activities that are unpaid, non-compulsory, and unrelated to family obligations [
18]. ABS [
19] data indicate that around a third of Australians engage in some form of volunteering within a 12-month period, with the highest rates among those aged 55–64 years (46 %) and 65–74 years (38 %). Previous studies suggest that volunteering has substantial health benefits for older people (for reviews see [
20-
22]). While causality is difficult to demonstrate due to the largely observational nature of data synthesized in reviews, evidence suggests that engaging in volunteering activities may provide beneficial social, physical, and cognitive outcomes for older people [
23-
32].
Volunteering has also been linked with higher levels of self-rated health, lower mortality rates, reduced risk of depression, and improved psychological well-being [
20,
30,
33-
38]. One of the mechanisms by which health benefits are produced by volunteering may be an increase in physical activity [
39], which is likely to be largely due to additional manual work and walking [
29]. However, there is a lack of physical evidence of this relationship, and little understanding of why it exists [
31] and which forms of volunteering are most effective in generating positive health effects [
40].
Motivational studies consistently demonstrate that an advantage of volunteering is that it gives older individuals an increased sense of meaning [
24,
41]. In a study of seniors’ conceptions of well-being [
42,
43], results showed that older people are interested in undertaking activities that are of benefit to others and that volunteering is salient in their deliberations about how they could achieve this outcome. However, a primary barrier was reported to be a lack of knowledge regarding volunteering opportunities and how they can be accessed. There appears to be a preference for word-of-mouth communications about volunteering opportunities, especially in the form of direct invitations to assist with specific tasks [
44-
46].
Volunteering is similar to physical activity in that participation rates are highest among those in better health and with higher levels of income and education [
47]. It is also similar in that individuals are likely to assess the costs and benefits associated with the activity in their commencement and continuation decisions [
48]. Unfortunately, little is known about how these decisions are made, and more research is needed to understand this phenomenon. Older people need particular consideration when developing health promotion messages because of their greater heterogeneity due to more extensive and varied life experiences, their stronger health-related motivations, and the physical deterioration that occurs with age that affects message processing [
43,
49-
51]. However, little is known about the most effective ways to communicate with older people with the specific purpose of motivating them to engage in activity in general and volunteering activities in particular [
52,
53]. In the case of physical activity, it has been suggested that focusing on the social benefits may be more effective than emphasizing the physical health benefits [
54,
55]. It is likely that a similar focus on social benefits in messages aiming to encourage volunteering behaviors may be effective with the target group. As older people appear to consider mental incapacity as being more undesirable than physical incapacity [
56], another approach may be to highlight the mental health benefits of participation in volunteering behaviors.
In summary, a growing body of research demonstrates the importance of combining physical, cognitive, and social activities to achieve healthy ageing. Volunteering can facilitate these activities and thus may have positive outcomes for older people. Little previous work has quantified the physical health benefits of volunteering, and even less has investigated the mental health benefits. In addition, previous studies have tended to use self-report data rather direct health measures [
30]. Understanding the full potential for volunteering to affect physical and mental well-being will provide policy makers with the evidence they require to determine appropriate investment in the volunteering sector, especially in relation to encouraging volunteering among older people who constitute an important resource for the community.
The aim of this study is to assess the relative and combined effects of volunteering on seniors’ physical and mental well-being. This aim will be achieved in the context of a randomized controlled study using an Australian population sample. The primary research objective is to test whether engagement in a volunteering program results in significant improvements to physical and mental health compared to control (usual lifestyle activities). The results can be used to inform public policy on this issue and develop appropriate strategies to encourage older people to participate in volunteer activities.