To keep the heart ticking, the key is to work out regularly. Light and moderate intensity exercises are considered to be cardio-protective.
Cardiovascular diseases have become a major contributor to disease related disability worldwide. The World Health Organisation (WHO) estimates indicate that cardiovascular disease accounted for 16.7 million deaths in 2000.
Causative agents
Many causative agents for this epidemic have been identified. Changes in lifestyle to a more sedentary type and physical inactivity are the crucial triggers. Both lead to obesity, diabetes mellitus, hypertension and lipid disorders, which in turn are the risk factors for a cardiovascular disease. Regular exercise of at least 30 minutes a day or brisk walking, cycling or working around the house are recommended to keep disease at bay.
How to stay healthy?
With advances in technology and industriali sation, the necessity of physical activity at work and in leisure has declined steeply. The National Institute of Health (NIH) in US recommends 30 minutes of moderately intense physical activity every day of the week.
Survival of the fittest
The cardio-respiratory fitness of an individual depends on his or her habitual physical activity, age, gender, heredity and coexistent diseases. Physical fitness is best measured by peak oxygen uptake, which is an index of energy expenditure. It is best quantitated by the unit “METS”. One MET is the measure of oxygen uptake by a person at rest and is equivalent to 3.5 ml O2/kg/mt. American College of Sports Medicine (ACSM) guidelines recommend 3 to 6 METS activity. Brisk walking, cycling and swimming are thus recommended.
As the level of fitness increases, a linear reduction in mortality can be noticed. Each increase of 1 MET in exercise capacity confers a 12 percent improvement in the survival in patients with coronary artery disease (CAD). ACSM guidelines say that a programme of regular exercise can improve fitness by 15-30 per cent in three to six months. Exercise improves lipid profile and glucose intolerance and also reduces obesity and blood pressure. The protective effect of physical activity is mainly due to the physiological changes that arise as a result of it. There is efficient oxygen supply and uptake by exercising the muscles. An increase in volumen of LV allows for a higher stroke volume. There is also efficient exercise induced vasodilatation of arteries that supply the working muscles and increase in activity of oxidative enzymes in exercising muscles. As a result of this greater efficiency in oxygen delivery and extraction, the normal cardiovascular response to sub-maximal exercise is attenuated in physically fit people.
Exercise for cardiac patients
Safety of exercise training in patients with heart disease and post coronary Artery Bypass Grafting (CABG) patients has been well established. However, it’s necessary that trained medical or paramedical personnel are present to supervise in initial few weeks. Light and moderate intensity exercises have proved to be cardio protective. Exercise reduces angina pectoris in those with CAD and heart failure in patients with LV systolic dysfunction.
Physical exercise produces physiological and biochemical changes within the body that improves the functioning of both skeletal muscles and the cardiovascular system. The intensity and duration of exercise in cardiac patients and those who have recovered from cardiac surgery is to be planned out by a rehabilitation physician. Ideally, an exercise protocal that achieves 70 to 80 per cent THR (220-age) is desirable. A precautions however, need to be taken.
* Avoid workouts within and one hour after meals.
* Avoid isometric and breath-holding exercises.
* Optimal room temperature is to be maintained and it is important to avoid excess humidity in the room.
* Add warm off and cool off periods of 15 minutes or more with strenuous exercises.
* Wear loose clothing during exercise.
Symptomatic cardiac patients with heart or lung dysfunction should attend exercise sessions in a rehabilitation centre, supervised by trained therapists.
Recommendations
It is recommended that a daily exercise programme involving at least 30 minutes of exercise equivalent to 5 to 6 METs is beneficial for adults. This will increase longetivity and prevent or retard the development of disease like hypertension, diabetes, CAD and stroke in patients with established cardiac diseases. It is necessary to attend a cardiac rehabilitation programme and work out an effective programme. Skeletal muscle injury and precipitation of ischemic events or heart failure can be prevented by gradually building up to the desired level of exercise.
Men over 40 years and women over 50 should consult a physician prior to starting a vigorous physical activity programme. In patients with a strong family history of CAD or those who have more than two risk factors for CAD, a medical evaluation including exercise stress tests are recommended.