Estimated read time: 2-3 minutes
This archived news story is available only for your personal, non-commercial use. Information in the story may be outdated or superseded by additional information. Reading or replaying the story in its archived form does not constitute a republication of the story.
Exercise lowers the risk for heart attacks.
Heart attacks occur when a blood clot forms in a narrowed region of an artery, where an atherosclerotic plaque has formed, an area less capable of opening up. The clot obstructs the artery, blocks blood flow, shuts off oxygen flow to heart muscle, and there you are: a myocardial infarction.
How does exercise work? For one thing -- and there are many things, which is why exercise is such an all-around good idea for promoting and maintaining heart health -- exercise subtly inhibits blood clotting. Exercise is anti-thrombogenic, to employ a $5 word.
The sequence of plaque development has been reasonably well worked out. When the lining of the arteries is continuously and chronically washed with blood with a high fat content, some of that fat will be absorbed and deposited in the wall of the artery. This can begin as early as adolescence. Fat in the arterial lining induces an irritant reaction that attracts calcium. The wall of the artery becomes rigid, further aggravating the mechanical stress on the plaque.
Although plaques are covered by a thin layer of fibrous tissue, where this is thinnest, it can tear. Suddenly the core of the plaque is exposed to the circulating blood, releasing a variety of clotting factors and attracting platelets, tiny cell fragments which normally close off tears in a vein or artery. A clot begins to form, and it is self-perpetuating. It can enlarge to fill or narrow the channel of the artery, and then the heart is in trouble.
Aspirin is advised for most people, middle-aged and beyond, because at a very small dose, clotting factors are partially disabled, not so much that you actually bleed but enough that clots are less likely to form.
A single bout of exercise stimulates the release of substances that make clotting less likely, and regular exercise, even of a modest nature, maintains them at a higher level and permits a greater ready reserve. Exercise is as effective as aspirin, has few risks and carries with it so many other benefits that it's hard to mount an argument against it.
Jay Caldwell is director of the Alaska Sports Medicine Clinic.
To see more of the Anchorage Daily News, or to subscribe, go to http://www.adn.com.
This material Copyright 2003 Anchorage Daily News, Anchorage AK
