Exercise and Heart Attack
Regular physical activity has long been regarded as an important component of a healthy lifestyle. Recently, this impression has been reinforced by new scientific evidence linking regular physical activity to a wide array of physical and mental health benefits. It has already been proved that regular physical activity can prevent formation of atheroma (block) inside your coronary artery. Intermittent bouts of physical activity, as short as 8 to 10 minutes, totalling 30 minutes or more on most days provide beneficial health and fitness effects. Physical activity has been defined as any bodily movement produced by skeletal muscles that results in energy expenditure. Epidemiologic research has demonstrated protective effects of varying strength between physical activity and several chronic diseases, including coronary artery disease (angina/heart attack), hypertension (high blood pressure), diabetes, osteoporosis (bone thinning), colon cancer and depressive illness. A midlife increase in physical activity is associated with a decreased risk of mortality. It has been estimated that as many as 250, 000 deaths per year in the United States, approximately 12 per cent of the total, are attributable to a lack of regular physical activity.
How does exercise prevent heart attack?
Exercise increases the blood level of high density lipoprotein (good cholesterol)
Reduces blood level of triglyceride, which is a risk factor of coronary heart disease.
Reduces high blood pressure
Enhances fibrinolysis (dissolute the solidified blood immediately)
Reduces blood sugar level in diabetics by increasing insulin sensitivity
Reduces the adhesiveness of the platelets, so that they can not unite each other to form thrombosis.
Exercise reduces the sensitivity of the heart muscle to adrenaline and noradrenaline so, reduces the chance of heart rhythm irregularity.
Physical activity recommendations :
The previous recommendation was 20 to 60 minutes moderate to high intensity --endurance exercise three or more times per week. But recent recommendations differ from the earlier report. It is now recommended that all adult should accumulate 30 minutes or more of moderate-intensity physical activity on most, preferably all days of the week (1). Adults who engage in moderate-intensity physical activity-ie, enough to expend approximately 200 calories per day, can expect many of the health benefits. To expend these calories, about 30 minutes of moderate-intensity physical activity should be accumulated during the course of the day. One way to meet this standard is to walk 2 miles briskly.
Intermittent activity also confers substantial benefits. Therefore, the recommended 30 minutes of activity can be accumulated in short bouts of activity : walking up the stairs instead of taking the elevator, walking instead of driving short distances, pedaling a stationary cycle while watching television. Those who perform lower-intensity activities should do them more often, for longer periods of times or both. People who prefer more formal exercise may choose to walk or participate in more vigorous activities, such as jogging, swimming or cycling for 30 minutes daily. Sports and recreational activities, such as tennis or golf (without riding a car), can also be applied to the daily total.
Most adults do not need to see their physicians before starting a moderate-intensity physical activity program. However, men older than 40 years and women older than 50 years who plan a vigorous program or who have either chronic disease or risk factors of cardiovascular disease should consult their physician to design a safe, effective program.
Exercise has got the following health benefits :
- Caloric expenditure and total time of physical activity are associated with reduced cardiovascular disease incidence and mortality.
- There is a dose-response relationship for this association.
- Regular moderate physical activity as short as 8 to 10 minutes, totaling 30 minutes or more on most days provide beneficial health and fitness effect
A number of physical and social environmental factors can affect physical activity behavior. Family and friends can be role models, provide encouragement, or be companions during physical activity.
The environment often presents important barriers to participation in physical activity, including a lack of bicycle trails and walking paths away from traffic, inclement weather and unsafe neighbourhoods. Excessive television viewing may also deter persons from being physically active.
Examples of common exercises :
[METs (work metabolic rate/resting metabolic rate). One MET represents the approximate rate of oxygen consumption of a seated adult at rest, or about 3. 5 ml min kg. The equivalent energy cost of 1 MET in kilocalories-min is about 1.2 for a 70 kg person or approximately 1 kcl kg hr. ]
Exercise but when, Morning or Afternoon?
The time of onset of myocardial infarction (heart attack) and other ischaemic heart events and arrhythmic episodes (irregularities of heart) display a circadian rhythm (variation of time of occurrence) with peak occurrence in the early morning between 6 AM and noon.
This may be related to morning surges of hormone cortisol, increased blood level of catecholamimes (adrenaline and nor-adrenaline) and greater platelet aggregability (increased chance of blood solidification by blood cells) that occurs in the morning as compared with the afternoon.
Since exercise may also precipitate ischaemic heart events, it has been postulated that it is safer to exercise in the afternoon than in the morning. But there was no statistically significant difference between the risk of exercising in the morning vs the afternoon.
The risk of untoward cardiac events during regular exercise is low in patients with heart disease, whether they exercise in the morning or the afternoon.
Data suggest that the answer to the clinical question of when patients with heart disease should perform regular, submaximal exercise is clear: AM and PM are both safe.
DR. BAREN CHAKRABORTY FCPS, FCCP, FACA, FRCP
The author is Sr. Consultant Cardiologist.
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