Physical exercise and cardiovascular risk
Physical exercise is a potent primary and secondary preventer of cardiovascular illness, particularly that due to coronary heart disease. Evidence continues to accumulate that taking up exercise to prevent cardiovascular disease, or to reduce its risk of recurrence in those already affected by it, is efficacious and not associated with any appreciable harmful effects, if performed with appropriate safeguards.
Regular physical exercise is thought to mediate its beneficial effects through:
- Reducing the incidence and severity of obesity and the consequent risk of type 2 diabetes (obesity being more important than inactivity in the risk of developing type 2 diabetes).
- Improved glucose tolerance.
- Enhanced fibrinolysis.
- Improved endothelial function.[3, 4]
- Decreased sympathetic tone and enhanced parasympathetic tone.
- Lowering of blood pressure.
- Improved lipid metabolism.
- Other factors, as yet unelucidated.
It is thought that physical inactivity roughly doubles the risk of coronary heart disease and is a major risk factor for stroke. Regular walking at a brisk pace and spending fewer hours per day sitting may be as effective in reducing risk as more vigorous exercise.As well as the direct physical benefits on the body's cardiovascular and metabolic parameters, exercise also provides benefits through reduction of the effects of stress, amelioration and prevention of depressive illness/anxiety in those who are at risk of, or suffering from, cardiovascular disease, and improved self-esteem. Interestingly, the beneficial effects of alcohol on reducing heart disease are not as measurable in those who exercise, as they are in 'couch potatoes'.
How much and how often?
There is no clear consensus on the basis of trial data as to the optimal duration, frequency and type of exercise in primary or secondary prevention of coronary artery disease. However, it can be agreed that exercise undertaken to prevent coronary artery disease, in order to be effective, should:
- Be sustained in the long term.
- Be regular, ie at least 4-5 days per week.
- Last for about 30 minutes
- Be of mild-to-moderate intensity, ie enough to make people feel warm and out of breath but not so vigorous as to cause extreme breathlessness.
What sort of exercise?
- Useful activities would include regular walking, cycling, swimming, gardening or dancing.
- Aerobic exercise is thought to be more beneficial and less risky than anaerobic exercise.
- Patients should be advised to avoid exertion that causes straining or raised intra-abdominal/intrathoracic pressure, such as weightlifting, etc, if they are inactive and/or have coronary artery disease.
- Sedentary people should start with mild exertion for short periods and then gradually build the duration and intensity of the exercise over a few weeks.
- It is best to avoid sudden, erratic bouts of exercise in middle age or in those with coronary artery disease, as there is good evidence that it increases the risk of myocardial infarction and sudden cardiac death in these groups.
- There is no evidence that vigorous, prolonged exertion provides any further benefit than moderate, gentle, aerobic exercise of moderate duration; however, more extreme exercise does appear to increase the risk of adverse cardiac events.
- Those who take regular exercise are much less likely to develop complications as a consequence of vigorous exercise. There is some evidence to suggest that the risk of adverse events due to exercise is increased in those who exercise early in the morning.
- There is evidence that the benefits of regular exercise are available to all, including healthy older patients, particularly in terms of peripheral blood flow mediated through enhanced endothelial nitric acid production.
Cardiac rehabilitation and secondary prevention of coronary artery events through exercise
- Any patients who have had a myocardial infarction or episodes of angina should be encouraged to incorporate exercise into their lifestyle in order to reduce their risk of further cardiac events.
- A history of myocardial infarction or angina is not a contra-indication to an ongoing exercise programme.
- Patients should take care to build exercise gradually if coming from a sedentary baseline and exercise within the limits of any angina, breathlessness or claudication.
- It is best to avoid outdoor exercise in very cold weather, in strong winds or exercising when experiencing chest pain.
- Any patient who has had a myocardial infarction should undergo initial assessment in a dedicated cardiac rehabilitation service; they will be given an exercise programme based upon their symptomatology and their exercise performance on a treadmill whilst having their heart rate response measured.
- It is essential that patients 'warm up' and 'warm down' before and after exercising, as a failure to do so can further increase the risk of cardiac events at the beginning of, and after, exercise.
- 'Warm-up' and 'warm-down' routines are taught as part of a cardiac rehabilitation programme.
- There is good evidence from many nations of the benefits of exercise prompted and sustained through cardiac rehabilitation programmes and patients should be strongly encouraged to enrol and participate in them.
Sexual activity after myocardial infarction or coronary revascularisation
- Although sexual activity is associated with an increased risk of cardiovascular events, the absolute rate of events is very small because exposure to sexual activity is of short duration and constitutes a very small percentage of the total time at risk for myocardial ischaemia/infarction.
- Sexual activity is the cause of less than 1% of all acute myocardial infarctions. The absolute risk increase for myocardial infarction associated with one hour of sexual activity per week is estimated to be 2 to 3 per 10,000 person-years.
- For a person with a previous myocardial infarction, the annual risk of re-infarction or death is estimated to be 10% (or as low as 3% if there is good exercise tolerance). Engaging in sexual activity transiently increases the risk of re-infarction or death from 10 chances in 1 million per hour to 20 to 30 chances in 1 million per hour.
- It is therefore reasonable that patients with cardiovascular disease wishing to initiate or resume sexual activity be evaluated with a thorough medical history and physical examination. Sexual activity is reasonable for patients with cardiovascular disease who, on clinical evaluation, are determined to be at low risk of cardiovascular complications.
- Exercise stress testing is reasonable for patients who are not at low cardiovascular risk or have unknown cardiovascular risk to assess exercise capacity and development of symptoms, ischaemia, or arrhythmias. Sexual activity is reasonable for patients who can undertake moderate physical activity without angina, excessive dyspnoea, ischaemic ST-segment changes, cyanosis, hypotension or arrhythmia.
- Cardiac rehabilitation and regular exercise can be useful to reduce the risk of cardiovascular complications with sexual activity for patients with cardiovascular disease.
- Patients with unstable, decompensated and/or severe symptomatic cardiovascular disease should defer sexual activity until their condition is stabilised and optimally managed. Patients with cardiovascular disease who experience cardiovascular symptoms precipitated by sexual activity should also defer sexual activity until their condition is stabilised and optimally managed.
- Patients with previous myocardial infarction who are asymptomatic or have no ischaemia with stress testing or who have undergone complete coronary revascularisation are at low risk of myocardial infarction triggered by sexual intercourse.
- Before the routine use of reperfusion therapy, it was recommended that sexual activity be avoided for six to eight weeks after myocardial infarction. However, because of participation of stable patients in cardiac rehabilitation exercise programmes, resuming sexual activity one week after myocardial infarction has proved safe. Therefore, resumption of sexual activity soon after uncomplicated myocardial infarction seems reasonable in the stable patient who is asymptomatic with mild-to-moderate physical activity.
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- Levine GN, Steinke EE, Bakaeen FG, et al; Sexual activity and cardiovascular disease: a scientific statement from the American Heart Association. Circulation. 2012 Feb 28 125(8):1058-72. doi: 10.1161/CIR.0b013e3182447787. Epub 2012 Jan 19.
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