Reports of people collapsing with cardiac arrest during sport raise an obvious question: is exercise dangerous for the heart? A report by Zakaria Sumon in Prothom Alo says the risk depends on the type and intensity of exercise and on how prepared the body is.
Exercise raises the muscles' demand for oxygen, so the heart pumps faster and harder and heart rate and blood pressure rise. A healthy body copes. But if plaque has already narrowed the coronary arteries, sudden intense effort can rupture the plaque and trigger a clot, blocking blood flow to the heart and causing a heart attack.
A study published in the New England Journal of Medicine analysed more than 1,200 heart attack patients and found that heavy exertion in the hour before can temporarily raise the risk. Among people used to regular heavy exertion, though, the extra risk was much lower.
The danger is greatest for those who have been inactive for a long time and suddenly sprint, lift heavy weights, play a football match without preparation, run long distances, climb hills or cycle hard. Someone who never exercises doing a day of very heavy physical work can put the same strain on the heart.
The American Heart Association advises inactive people to start with light exercise and build up time and intensity gradually. People with high blood pressure, diabetes or high cholesterol, or anyone past middle age who has not exercised for a long time and wants to start hard training, should see a doctor first.
Warming up with a walk or easy movement before raising the pace is safer. The report lists PubMed, the New England Journal of Medicine, heart.org and Reuters as its sources.
Photo: park jogging track (file), Mk2010 / Wikimedia Commons (CC BY-SA 3.0)
Source: Prothom Alo
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