Despite public physical activity guidelines and the established benefits of regular exercise, almost 50% of adults worldwide fail to meet aerobic physical activity targets [6] and approximately 90% fail to meet resistance exercise recommendations [7]. In 2014-15, 54% of Australian adults were either sedentary or inactive, a decrease from 56% of adults in 2011-12
22 and 62% of adults in 2007-08. In comparison to these survey-response statistics, accelerometer- based studies provide a more objective measure of physical activity by measuring movement counts. These data indicate that only 5% of U.S. adults meet minimum physical activity recommendations [100], with similar findings in Swedish [101] and Australian adults who spend just 4% of waking hours engaged in moderate- to vigorous-intensity activity [102]. A significant proportion of the adult population in developed countries are therefore at an increased chronic disease risk due to insufficient physical activity.
Conservative estimates indicate worldwide healthcare costs attributable to inactivity exceed 67.5 billion international dollars annually [103]. A pooled analysis of US and European prospective cohort studies involving 661,137 men and women with a median 14 years of follow-up found a dose-response relationship between increasing levels of leisure-time physical activity and reduced cardiovascular, cancer and overall mortality risk [53]. Compared to no leisure-time physical activity, a 20% lower mortality risk was associated with meeting minimum physical activity guidelines with greater risk reductions for higher levels of activity [53]. Similar dose-response relationships have been observed between total reported physical activity and the risk of developing diabetes, ischaemic heart disease, ischaemic stroke, breast and colon cancer [104].
Engaging people in an exercise program and maintaining their involvement are critical steps to improving health and fitness and decreasing chronic disease risk. Around 50% of people who begin an exercise program drop out within the first three to six months, a rate that has persisted over the past 30 years [34]. Indeed, attrition rates between 30% and 74% have frequently been reported by 3- to 6-month workplace exercise intervention studies [21, 24, 25, 105-109]. Buckworth and colleagues [34] state that the identification of barriers and facilitators
23 to exercise participation is crucial when developing interventions to foster the adoption and maintenance of regular exercise. The environment, policy and individual factors all influence one’s physical activity participation and are linked to both acute and chronic health and fitness outcomes (physiological and psychological) [34]. It is therefore important to consider these multiple factors when designing an exercise program to maximise adherence and program effectiveness. For example, access to exercise facilities, attitudes and beliefs around exercise along with current and previous exercise experience should all be taken into consideration when prescribing an individually-tailored exercise program, as is done during a standard consultation with an Exercise and Sports Science Australia accredited exercise physiologist.
Many of the techniques used to promote exercise originated from psychological theories of motivation and behaviour change. The Transtheoretical Model of behaviour change (TTM; also known as the stages of change model) provides a framework for understanding motivation for behaviour change as well as actual behaviour change [34]. Originally developed to describe changes to addictive behaviour, the TTM was expanded to include the adoption of preventative health behaviours, and has now been applied in many exercise and physical activity studies [34]. The TTM includes three levels: stage of change, constructs hypothesised to influence behaviour change, and level of change. This is the stage model most frequently applied to exercise. The first level of the TTM involves five distinct stages in relation to exercise behaviour; pre-contemplation, contemplation, preparation, action and maintenance [34]. A direct relationship has been observed between a person’s stage of change and the number of minutes they are physically active each week [110], and moving forward one or more stages has been associated with increases to CRF [111].
24 The second level of the TTM includes three constructs that are hypothesised to influence behaviour change: self-efficacy to overcome barriers, decisional balance (pros vs. cons of target behaviour), and processes of change [34]. Instruments to measure these mediating mechanisms underlying motivation to change have been developed and validated for exercise [112-114]. Longitudinal evidence suggests that exercise self-efficacy is generally lowest in the early stages (e.g. pre-contemplation) and increases as the individual moves from a sedentary lifestyle to one involving the long-term maintenance of regular exercise [115-117]. However, it is unknown whether higher exercise self-efficacy is the result of past success with exercise and this experience is a determinant of current behaviour; or whether people are more active because they have a higher exercise self-efficacy. Decisional balance (or decision-making theory) is another construct from the TTM that is believed to influence exercise behaviour. This theory attempts to explain how people decide to engage in a behaviour based on the perceived benefits and costs of the behaviour [118]. People in the earlier stages of change tend to perceive more disadvantages and barriers to engaging in exercise, such as a lack of time, motivation or energy [112, 119].
One criticism of workplace exercise programs is that they tend to attract individuals who are highly motivated or are already physically active [120-122], and fail to engage the vast majority of sedentary employees who lack the motivation to change. Recent data on university employees found that those who were already active (i.e. in the action or maintenance stages) when enrolling in a 6-week workplace physical activity challenge were four times more likely to complete the competition [122]. Data on the number of employees in each respective stage of change provides useful information for designing both recruitment strategies and exercise programs to more effectively engage both inactive and active individuals. For example, if the majority of a workplace population are categorised as pre-contemplators or contemplators
25 (stage one or two), researchers may consider designing intervention recruitment strategies that seek to more effectively attract inactive individuals by emphasising that the proposed exercise program is available to everyone regardless of current or previous activity participation or fitness levels. This may help to dispel the perception that only fit, active people should take part. Stage of change in relation to physical activity participation was measured in Chapter 3, the findings of which helped to inform the design of the recruitment strategies used for the exercise interventions conducted in Chapters 4 and 6. Specifically, one-third of surveyed university employees were not maintaining regular physical activity participation and therefore intervention recruitment emphasised that prior exercise experience or having a currently active lifestyle was not required for participation in the exercise studies.
Social ecological models provide a framework for understanding the numerous factors and behaviours that act as facilitators or barriers to exercise participation. However, in contrast to the TTM which focuses on the individual (i.e. attitudes, beliefs, cognitions, behavioural skills and experiences), social ecological models consider a range of factors including the broader community, organisations, culture, policies, and constructed and natural environments to explain behaviour and guide interventions [34]. This approach recognises that health behaviours are part of a larger social system (or ecology) of behaviours and social influences, and that lasting changes in health behaviours require supportive changes in the system as a whole. Due to the number of factors that influence behaviour, exercise interventions may be more effective when they target changes in four domains: intrapersonal, social environmental, physical environmental, and policy. Each of these domains can impact the behaviour of an individual [123], and while these components remain constant across settings, the specific examples within each will vary depending on the population group [124]. According to Sallis and colleagues [125], the basic principles of ecological perspectives are that: (1) multiple levels
26 of factors influence behaviour; (2) influences interact across levels; (3) multilevel interventions should be most effective; and (4) models are most effective when they are behaviour specific [125]. These models assume an interdependence between people, their behaviour and the environment, which collectively affects the adoption and maintenance of behaviour [34].
The intrapersonal level of the social ecological model includes personal factors that increase or decrease the likelihood of an individual being or becoming physically active. Strategies addressing this level include education and mentoring programs focusing on changing someone’s knowledge, attitudes, behaviour and skills. At the social environment level, strategies used to promote exercise include community education, support groups, workplace incentives and social marketing campaigns. These aim to promote positive community attitudes and awareness towards exercise participation. Exercise takes place in both natural and manufactured environments, which are likely to influence the amount and type of activity that takes place. Strategies focusing on the physical environment, for example the installation of exercise facilities, should precede education and awareness programs in order for exercise behaviour change interventions to be most effective [126]. In addition, both formal (local, state or federal government actions) and informal local policies (organisational statements or rules) have the potential to affect exercise behaviour.
There is some evidence that physical activity and exercise programs targeting multiple levels of behaviour are more likely to lead to greater changes and longer lasting maintenance of physical activity than those that don’t [126]. Specific to the workplace, Heirich and colleagues [127] found that a multilevel approach achieved greater exercise session attendance and reductions in cardiovascular risk factors compared to simply providing a staffed exercise facility (i.e. single-level approach). The author’s concluded that a systematic, ongoing outreach
27 method to recruit employees for exercise programs may be more effective than simply the presence of fitness facilities without such outreach. This was supported by a review of health promotion programs across 10 U.S. federal agency workplaces involving a total of 3,388 employees [128]. The review found that workplace health promotion programs using multilevel strategies (i.e., management support, social environment, organisational resources and marketing) reported higher participation levels, especially among minority and lower- position employees [128]. The exercise interventions that were conducted as part of the research involved in this thesis were underpinned by the social ecological model, in that: 1) participants were individually assessed and were provided individual exercise prescription (intrapersonal); 2) participants could exercise in a shared environment (social environmental); 3) onsite exercise facilities were available as part of some of the intervention arms (physical environmental); and 4) participants could choose to exercise before, during or after working hours at no cost (policy).