The concept of exercise for health-related benefit is not new. Hippocrates recognised the merits of physical activity as a potential fountain of youth.
But lifestyles have changed dramatically since his time and never has the issue of exercise for health been more important than now. Our sedentary society is characterised by obesity and lifestyle-associated medical complaints, many of which will benefit from a regular exercise regime.
The benefits of exercise
Regular exercise is linked with significant reductions in morbidity and mortality associated with cardiovascular disease, diabetes, obesity, cancer, arthritis and osteoporosis; reduced anxiety and depression; enhanced well-being; and improved physical function.
A third of deaths from CHD could be prevented if people started taking more exercise. Exercise is also as effective as an antidepressant in mild-to-moderate depression.
In spite of this, exercise prescription - the recommendation of a structured and progressive physical activity programme for health-related benefit - is all too often a forgotten area of healthcare.
However, just as physicians are responsible for any drug scrip they write, the potential benefits and risks of exercise for specific populations must be understood by the prescriber.
The aims when writing an exercise prescription are to accurately identify those in need and to gain their enthusiasm and confidence and empower them to take responsibility for their exercise programme. To identify the minority who may be put at risk by exercise; develop a prescription that is realistic, simple, effective and safe; and monitor compliance and progress.
Assessment for exercise on prescription should include current and past physical activity habits, preferred forms of physical activity, goals of the exercise programme, and cardiovascular risk.
Current motivation and barriers to exercise and beliefs about its benefits and risks should be ascertained. The assessment should also include concurrent disease, cardiovascular risk factors, physical limitations precluding certain activities, exercise-induced symptoms, social support for exercise participation, time and scheduling considerations, and a medication profile.
While the most common adverse effect of exercise is musculoskeletal injury, the most serious is sudden death. This is rare, with sudden deaths occurring in six to seven per 100,000 exercisers or one in every 396,000 hours of exercise.
In people under 35 years of age, it is most likely due to hypertrophic obstructive cardiomyopathy, Marfan's syndrome, myocarditis or anomalous coronary artery anatomy. In those older than 35 years, the usual cause is atherosclerosis.
Patients with known cardiovascular or pulmonary disease, diabetes or who are asymptomatic but with more than one cardiac risk factor may need specialist input and exercise testing before embarking on an unaccustomed exercise regime (see box above).
Those with moderate or severe cardiovascular or pulmonary disease will need close supervision.
Patients with musculoskeletal problems may also need altered programmes and input from physiotherapists.
It is important to be aware of the absolute and relative contraindications to unaccustomed exercise.
Recommendations for exercise in pregnancy are available. It has also been recommended that men over 40 years of age and women over 50 who suddenly want to embark on a new strenuous exercise programme should first undergo specialist assessment and stress testing.
Choosing the right exercise
The initial step in writing the prescription is activity selection. The most effective activities for aerobic training employ large muscle groups that are maintained in continuous and rhythmic motion. Examples include walking, jogging, running, cycling, swimming, rope skipping, rowing and stair climbing.
Exercise should be undertaken on most days, with a minimum of three 20-60 minute sessions per week.
However, note that sessions can be divided into portions lasting at least eight minutes. Exercise intensity should be moderate (50-69 per cent maximum heart rate or perceived exertion rating of six or seven out of 10).
The regimen should include a short warm-up to reduce the risk of musculoskeletal injuries and cardiac events, a cool-down and stretches to increase flexibility.
Resistance training with free weights is important to increase muscle mass, metabolic rate and function.
The prescription should be phased. The initial phase should last four to six weeks with the goal of increasing the frequency of sessions.
The improvement phase should last four to six months, with the goal of increasing the duration and intensity of sessions. The maintenance phase aims to maintain cardiorespiratory fitness.
The reluctant exerciser is often the most needy. Tackle reluctance by actively encouraging interest, providing written information, devising attractive goals and employing compliance strategies, such as tailored programmes and exercise diaries, and providing support and follow-up.
While many of the processes described here may appear time consuming, there are ways of improving efficiency in the referral process, including use of a pre-assessment form, and involving a practice nurse or physiotherapist.
There are more than 1,300 exercise referral schemes in the UK, although just 42 per cent of GPs have access to them. There is also considerable variation between schemes.
Most are run by local authorities and GPs can refer patients by completing a referral form and sending it to the scheme co-ordinator, typically based at a public leisure facility. The patient is taken through a supervised programme, usually lasting 12 weeks.
Recommendations for an independent programme are then made and, ideally, feedback sent to the referring GP.
Dr Speed is consultant in rheumatology, sports and exercise medicine at Addenbrooke's Hospital in Cambridge.
Contraindications for exercise
- Recent acute MI.
- Unstable angina.
- Ventricular tachycardia and other dangerous arrhythmias.
- Dissecting aortic aneurysm.
- Acute congestive heart failure.
- Severe aortic stenosis.
- Active or suspected myocarditis or pericarditis.
- Thrombophlebitis or intracardiac thrombi.
- Recent systemic or pulmonary embolus.
- Acute infection.
- Untreated or uncontrolled severe hypertension.
- Moderate aortic stenosis.
- Severe subaortic stenosis.
- Supraventricular arrhythmias.
- Ventricular aneurysm.
- Frequent or complex ventricular ectopy.
- Uncontrolled metabolic disease (for example diabetes) or electrolyte abnormality.
- Chronic or recurrent infectious disease, such as hepatitis.
- Neuromuscular, musculoskeletal or rheumatoid diseases that are exacerbated by exercise.
- Complicated pregnancy.
Cardiovascular risk factors
Patients with more than one cardiovascular risk factor require specialist assessment prior to an unaccustomed programme.
- Family history of coronary artery disease or sudden death in a man under 55 or a woman under 65.
- Obesity (BMI>30kg/m2 or waist >100cm).
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Long B J, Calfas K J, Wooten W et al. A multisite field test of the acceptability of physical activity counseling in primary care: project PACE. Am J Prev Med 1996; 12: 73-81.
Dugdill L, Graham R C, McNair F. Exercise referral: the public health panacea for physical activity promotion? A critical perspective of exercise referral schemes; their development and evaluation. Ergonomics 2005; 48: 1,390-410.