Background
Physical inactivity is a modifiable risk factor for a multitude of chronic conditions including heart disease, stroke, diabetes mellitus, depression and a range of musculoskeletal disorders [
1‐
7]. Individuals who engage in regular moderate physical activity are less likely to die prematurely [
8‐
11]. In the U.S., physical inactivity now closely follows tobacco use as the leading effective cause of death [
12‐
14]. Approximately 250,000 deaths could be prevented in the United States each year if citizens were to become moderately physically active [
15]. In addition to personal health impacts, physical inactivity also places a considerable financial burden on individuals and the economy as a whole. In 2006, the cost of physical inactivity to the U.S. economy was estimated at $251 billion [
16]. Negative impacts of physical inactivity are not limited to the U.S. population. The World Health Organisation (WHO) has identified physical inactivity as the fourth leading effective cause of death globally [
17].
There are a range of benefits associated with increasing physical activity [
1,
4‐
7,
18‐
20]. Immediate gains include improved musculoskeletal and mental health as well as cardiovascular and respiratory benefits [
18]. Medium and longer term benefits are wide ranging. Physical activity reduces the severity of existing health conditions and can prevent a range of further co-morbidities [
4,
6,
7,
19]. In patients with multiple chronic conditions, physical activity has been associated with a reduced 42-month all-cause mortality rate [
20]. Among people who are obese, becoming physically active can reduce the chance of chronic health conditions to the level of people who are within a healthy-weight range but are not physically active [
5]. Benefits are not limited to youth or young adults. Resistance exercise training among octogenarians can improve muscle strength, mobility, dynamic balance, reduce falls and lead to more spontaneous physical activity [
21,
22].
The benefits of physical activity are dependent on the intensity, duration and frequency with which it is undertaken. The American College of Sports Medicine and the American Heart Foundation recommend a minimum of five 30-minute sessions of moderate intensity aerobic activity (e.g. brisk walking or equivalent) or three 20-minute sessions of vigorous intensity aerobic activity (or a combination of both) [
23]. However, it is noteworthy that reducing sedentary time, regardless of how much time is spent in moderate or vigorous physical activity, has also been associated with reduced mortality [
24].
Despite the known benefits of physical activity, a large proportion of people in developed and developing nations do not meet minimum recommendations for physical activity [
25]. More than 95% of adults in the United States do not meet the recommended level of 30 minutes of moderate intensity physical activity per day [
26]. More than 25% are completely sedentary during their leisure time [
25]. Many explanatory factors have been proposed; most relate to societal changes during recent decades that have contributed to the commonality of sedentary lifestyles [
27‐
32]. These factors include the increased popularity of sedentary behaviours in recreational and social pursuits, educational settings and occupational activities [
30,
31]. This transition to sedentary lifestyles has been accelerated by the rapid advancement of information technologies used in recreation, education and occupational contexts [
27‐
29,
32].
The burden of physical inactivity will increase as the population ages. Between 2000 and 2040 the U.S. Census Bureau predicts an increase in the number of citizens older than 84 years from 3.5 million to 8–13 million [
33]. This represents a doubling or tripling of this age group. This substantial growth in older adults will not be offset by equivalent growth in younger age groups. The increasing relative proportion of elderly people is not limited to the U.S. but is occurring throughout developed nations [
33]. The increase will continue to accelerate after 2011 when the first of the baby boom generation will reach 65 years of age [
33].
Many diseases that are considered to be related to aging (e.g. cardiovascular disease, stroke, musculoskeletal disorders) can be prevented or alleviated through regular physical exercise [
34]. This intensifies the need for suitable physical activity behaviour change interventions targeted at priority groups. Targeting effective physical activity behaviour change interventions to priority population groups will not only minimise the personal impacts of inactivity. It will also reduce the extensive financial burden of healthcare costs associated with the sequelae of physical inactivity.
Medical professionals have been identified as having the potential to be powerful agents for physical activity promotion [
35‐
43]. During the course of their existing work they reach a large proportion of the population [
44‐
47]. Research from the United Kingdom indicates 90% of the population visit their primary care physician at least once within each three year period [
48]. Moreover, visits to a medical professional become more frequent as people age [
37]. Medical professionals are also respected sources of preventive health promotion with patients listing their primary care physician as a desired and expected provider of preventive care information [
37,
39,
41]. Furthermore, messages from medical professionals can have a catalysing effect on motivating change in exercise-related health behaviours [
36,
40,
42,
43]. This effect is not isolated to physical activity and has been observed in other health behaviours; such as smoking cessation [
49,
50].
The potential for medical professionals to impact physical activity behaviours amongst their patients has led to repeated recommendations for physical activity promotion to be incorporated into routine clinical practice [
35,
38,
51]. The U.S. Preventive Services Task Force (USPSTF) is an independent panel of prevention and evidence-based medicine experts, composed of primary care providers [
52]. The USPSTF conducts scientific evidence reviews and published its first report on clinical preventive services in 1989 [
52,
53]. The report stated that clinicians will be more effective if they address the health behaviours of their patients rather than by performing usual screening tests and physical examinations [
53]. To illustrate this point, epidemiological calculations have indicated that 205 45-year old women would be required to undergo mammography screening to prevent one premature death [
54]. This is in contrast to one premature death being prevented for each 16 of these women who become sufficiently physically active [
54]. Recommendations for primary care providers to incorporate physical activity counselling into their routine practice have been echoed by other organisations in the policy community (e.g. the American College of Preventive Medicine in 2005 [
51] and the Australian Heart Foundation in 2006) [
35].
Despite these recommendations, medical professionals still incorporate very little physical activity promotion into their routine practice [
55‐
59]. In one study among a diverse sample of U.S. adults, only 28% of respondents reported receiving advice about physical activity from a physician [
55]. Of these respondents, less than half received help with formulating an activity plan or follow-up support [
55]. It is clear that existing approaches to the management of inactive patients in day to day practice are flawed. In this paper we examine whether physical activity promotion by medical professionals is feasible and effective as part of their routine care for inactive patients and we discuss an alternative perspective on this role. To inform this discussion we have considered peer reviewed empirical research as well as recommendations or statements from government and health organisations.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
SM and MS contributed to the design, planning, drafting, appraisal and editing of the manuscript. Both authors read and approved the final manuscript.