Risks of Exercise
It should be remembered that running or any other vigorous exercise does not by itself confer immunity to the body and to coronory heart disease. In fact, vigorous exercise carries a slight increased risk of sudden death, a term usually associated with fatal heart rhythm abnormalities.
For this reason, people with a cardiovascular risk factor such as a family history of premature heart disease, high blood cholesterol, or chest pain should not take up exercise without medical assessment and supervision.
On the other hand, virtually everyone can enjoy the benefits of exercise if exercise programs are carefully designed to meet individual needs and if exercisers are taught to recognize warning signs that indicate they should stop and rest or possibly seek medical help.
What Research Shows
The effects of exercise have been difficult to document in long-term, controlled clinical trials. This is due to the difficulty of documenting consistent and comparable activity levels in large groups of people. There is still no definitive survey proving that regular exercise will lower heart disease rates. However,there are numerous epidemiologic studies—that is,retrospective surveys examining the health and habits in large groups of people—that strongly suggest that the benefits of exercise include avoiding coronary heart disease and lengthening life.
Here is one example
: bus drivers,who sat most of the day, and bus conductors, who were more active. The conductors had a significantly lower rate of heart attacks. However, this study left key questions unanswered, including whether the conductors may have been drawn to their active jobs because they were in better physical condition in the first place and whether the drivers may have been subjected to other factors, such as stress, that were not accounted for by exercise level alone. Other studies,including those of physically active men have shown an association between exertion and heart health, but again no causative link was shown; in some countries, such as Finland, physically active who ate that country’s typical high-fat diet showed no protection against heart disease and, indeed, had a high rate of heart attacks.
The most recent showed that among 17,000 who aged 35 to 74, those who expended at least 2,000 calories a week in exercise (including light activities such as walking around the office) had a significantly lower death rate from heart attack than those who were sedentary. Interestingly,he death rate rose slightly at the very highest levels of exertion; moderate, rather than extremely strenuous, activity appeared to be the protective factor.