Heart disease and physical activity

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:¹

• 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).²

• 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.⁵

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'.⁶

It is recommended to do at least one or both of the following:⁷

• 150 minutes of moderate intensity exercise per week, eg, swim, cycle or brisk walk. Moderate intensity exercise should make a person feel warm with increased breathing, but be able to talk comfortably with others.

• 75 minutes of vigorous intensity exercise per week, eg, running, stairs, playing sport. Vigorous intensity exercise should cause fast breathing with difficulty talking.

Exercise undertaken to prevent coronary artery disease, in order to be effective, should:⁸

• 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.

• 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.⁹

• 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.⁹

• 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.¹⁰

• 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.

For any person who has had a myocardial infarction, advise to be physically active and to avoid prolonged sedentary behaviour:¹¹

• Exercise regularly, in order to increase exercise capacity. Ideally, as part of a comprehensive exercise based cardiac rehabilitation programme.

• Exercise advice should take into account the person's current and past activity levels, comorbidities, personal circumstances, and preferences.

• In general, the aim is at least 150 minutes per week of moderate-intensity aerobic activity (to the point of slight breathlessness). Some moderate intensity activities can be incorporated into everyday life and include brisk walking, using stairs, and cycling.

• Advise muscle‑strengthening activities on 2 or more days a week that work all major muscle groups (legs, hips, back, abdomen, chest, shoulders and arms).

• Encourage people who are unable to perform moderate‑intensity physical activity to exercise at their maximum safe capacity and increase the duration and intensity of activity as fitness improves.

Sexual activity can be resumed when comfortable to do so, usually about four weeks after an MI. Sexual activity presents no greater risk of triggering a subsequent MI in a person than if they had never had an MI.