Healthy ageing: what role can physical activity play?

Nonetheless, physical activity remains a poor relation in population disease prevention. In contrast to exponential increases in the volume of research in exercise science or broader disease prevention, research into physical activity in the elderly has remained quite static over recent decades.⁴ Our purpose was to review the available evidence for health benefits of physical activity among older adults. A summary of our key points is given in the Box.

Population studies in diverse cohorts (such as 40 000 Iowan postmenopausal women and 472 elderly Dutch men) report similar findings -- a graded dose-response relationship between activity and all-cause mortality and coronary heart disease deaths.^5,6 A South Australian study identified a mortality risk 74% greater in elderly people who were completely sedentary, compared with the (mostly moderately) active.⁷ Further, even those aged over 60 years who change from being sedentary to engaging in at least moderate levels of activity accrue a clear health benefit.⁸

New findings repeatedly confirm that aerobic or vigorous activities are not essential for these cardiovascular benefits. For those who are sedentary, accumulating half an hour of moderate activity on most days of the week seems sufficient. This finding is replicated across studies which adjust for other risk factors and for clinical comorbidity, and which measure physical activity in diverse ways. This notion is particularly important for older adults, where adherence to physical activity will be much more likely if they perceive they are capable of performing the activity, such as moderate walking.⁹

There is good evidence that regular moderate activity protects against the development of diabetes in populations quite independent of body weight.^2,3,10 Up to half of people with diabetes are completely sedentary,¹¹ presenting a further clinical opportunity for secondary prevention, as physical activity is part of optimal management. Moderate physical activity may also reduce the risk of ischaemic stroke in the elderly,¹² and there is clear evidence, pooled across almost 30 studies, that physical activity reduces colon cancer risk, and may have a role in reducing breast cancer incidence in postmenopausal women.^2,3 In addition, physical activity is recognised as being associated with improved mental health, and is a clinical approach to mild anxiety and depression.² Cohort studies in the elderly show that more active people have a reduced risk of developing depression, and are more likely to maintain wellbeing.¹³ Clinical data suggest that moderate exercise regimens are anxiolytic, but that vigorous activity may have less effect, or even be counterproductive, among older adults. Finally, the quality and duration of sleep may be improved by activity, both for those living in the community¹⁴ and for nursing home residents.¹⁵

One important idea raised by the epidemiological literature is the notion of "compression of morbidity". Population studies suggest that the "disability-free years" can be increased in people who remain active,¹⁶ and that overall healthy lifestyles could postpone disability by up to five years.¹⁷ This has ramifications for improved functional status and quality of life.

The concept of risks versus benefits of activity is worth exploring. The transient increases in the risk of acute cardiac events and sudden death following bouts of vigorous activity are not found for moderate activity, and overall, even for vigorous activity, the benefits outweigh the risks. This provides further support for encouraging moderate activity in middle-aged and older adults.

Physical activity can help improve balance. This in turn helps older people by improving mobility and functional capacity, and reducing the risk of falls and injuries. Regular, gentle exercise classes, involving aerobic, strength, balance and coordination activities, improve balance when undertaken twice weekly over 12 months.¹⁹ Even a supervised program of gentle exercise such as tai chi may help to maintain balance.²⁰

Flexibility is another domain of physical performance that is necessary for daily activities such as climbing stairs, rising from a chair or bed, or walking. The evidence is less clear here, but some studies have shown yoga and flexibility training, supervised aerobics classes and walking and upper-body training can benefit flexibility.²¹

Two key public health issues related to these areas of physical functioning are osteoporosis, and falls and injuries. Some studies indicate that older people who have stayed active have significantly lower losses of bone mineral density than their sedentary counterparts. However, as bone mineralisation is completed by late adolescence, strategies later in life may have less of a role in preventing osteoporosis. The American College of Sports Medicine concluded that functional loading through physical activity exerts a positive influence on bone mass, but that the types of program that may be most effective in producing beneficial results are still uncertain.²¹

Physical activity is a beneficial component of falls prevention, because of its effects on muscle strengthening and balance, and possibly on bone density. In the meta-analysis of the seven Frailty and Injuries Cooperative Studies Intervention Trials (FICSIT), participation in an exercise program was found to reduce the risk of falling, although some programs were supplemented by education and other interventions.²² The Cochrane review also found that activity had a beneficial role, particularly when supplemented by additional measures such as medications review and home modification among elderly people identified as at risk of falling.²³ Many of these studies used supervised rather than at-home exercise interventions.

The frail elderly have typical problems that may make physical activity more difficult. Many may benefit from more moderate or even light activities; many of these can be carried out in residential settings and community centres. Apart from walking programs, other locally based interventions to improve mobility, increase strength and improve balance can be implemented and achieve improvements in this age group.^15,21 In addition to strength training, working to reduce polypharmacy, and making residential environments more physical activity friendly are also important. A recent controlled trial has identified positive outcomes of intensive exercise and resistance training among 100 hostel residents with a mean age of 87 years -- even in this frail elderly group physical activity, gait velocity and muscle strength improved.²⁴

Recommending physical activity to people over 65 is cost effective,²⁵ and a worthwhile part of many patient encounters in general practice. The counselling objectives are to identify achievable, moderate activities, increase confidence among patients that they can perform the activity, and highlight the importance of these activities in delaying disability. It is useful to know about local programs for referring patients to, and to encourage people to exercise with someone else. A New Zealand study identified general practice-based advice as being more effective if focused on written "exercise prescriptions" rather than verbal advice alone.²⁶ However, it is not easy to train doctors to promote physical activity to the elderly,²⁷ and other strategies may support this process.

Given the time constraints of practice, allied health professionals may provide specialised counselling in this area. Another New Zealand study ascertained lower rates of falls among women aged over 80 years who were referred to a physiotherapist for an exercise intervention delivered through general practice.²⁸ These improvements were maintained even at two years of follow-up. In a Victorian controlled trial, education of practitioners, extensive GP advice and home follow-up increased physical activity time per week among patients aged at least 65 years.²⁹ Further, in this issue of the Journal, Halbert and colleagues show that having a qualified exercise scientist in the GP's surgery to provide detailed advice and exercise plans provided a sustained increase in self-reported physical activity.³⁰ Thus, adjunctive methods like these may enhance the range of health outcomes, and achieve more than GP advice alone.

It appears that many of the benefits of activity are reasonably acute, and it may be recent physical activity which confers many of the chronic disease and musculoskeletal benefits.^21,31 Hence the advice "use it or lose it" should be as prevalent as antismoking messages. Given the credibility with which doctors' advice about exercise in older adults is perceived in the general community,³² each consultation presents an important -- and possibly overdue -- opportunity for promoting health to older adults.

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National Centre for Health Promotion, University of Sydney, NSW.
Ben J Smith, MPH, Research Assistant.

Reprints will not be available from the authors.
Correspondence: Professor A E Bauman, Epidemiology Unit, Locked Bag 7017 Liverpool BC, NSW 1871.

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