March 23, 2011

Sex, Exercise Boosts Short-term Heart Attack Risk

Exercising or having sex nearly triples a person's chances of having a heart attack in the hours immediately afterward, particularly if the person rarely performs those activities, according to a new analysis published Wednesday in the Journal of the American Medical Association.

However, the absolute risk is small, and even lower among those with who regularly engage in physical activity, the researchers said.

People who exercise regularly have a much smaller risk of having a heart attack immediately after sexual or physical activity, said Dr. Issa Dahabreh of Tufts Medical Center in Boston, lead author of the analysis.

"It would be really bad if someone thought our paper means people should not exercise," he said.

"If anything, it's the opposite."

The systematic review and meta-analysis analysis combined results from 14 studies involving more than 6,000 patients who had suffered heart attacks, or who had died suddenly from a heart problem.  Most of the patients were in their late 50s and early 60s.

The analysis examined what the people were doing during the hour or two prior to their heart attacks, and compared that to the same people's activity on typical days without major heart problems.

The researchers found a 3.5 times increased risk between episodic physical activity and heart attack.  There was also evidence of an increase in the risk of sudden cardiac death triggered by episodic physical exertion.

Overall, episodic sexual activity was associated with a 2.7 times increased risk of heart attack.

However, because exposures of episodic physical exertion and sexual activity are infrequent, the absolute risk of these activities triggering an event for any one person is extremely low.

"If you were to follow 10,000 people for a year and if they all decided to increase their physical activity by an hour a week, you could expect to see two to three more heart attacks," Dr. Dahabreh said.

For most people, that risk is offset by the benefits of exercise.

Additionally, the more frequently a person exercises, the less risk they have of exercise or sex triggering a heart attack, the analysis found.

"People who exercise regularly have a much smaller increase in risk, if any," Dr. Dahabreh says.

According to the analysis, study participants who were more physically active appeared to be less susceptible to a heart attack following sex or a workout.  For this subgroup, the risk of heart attack or sudden cardiac death triggered by episodic physical activity was decreased by 45 percent and 30 percent, respectively, for each additional time per week a person was worked out.

"Habitual activity levels significantly affected the association of episodic physical activity and MI (myocardial infarctions, or heart attacks), episodic physical activity and SCD (sudden cardiac death), and sexual activity and MI; in all cases, individuals with lower habitual activity levels had an increased relative risk for the triggering effect," the researchers wrote.

The researchers concluded that routine physical activity lessens the increased risk of MI and SCD in the two hours after physical or sexual activity.

"We found a significant association between episodic physical and sexual activity and MI, and suggestive evidence of an association between episodic physical activity and SCD," they wrote.

"Most importantly, these associations appear to be strongly modified by habitual physical activity, with individuals with higher habitual activity levels experiencing much smaller increases in risk compared with individuals with low activity levels."

"In view of this, as well as the small absolute magnitude of the risk associated with acute exposure to episodic physical or sexual activity, our findings should not be misinterpreted as indicating a net harm of physical or sexual activity; instead they demonstrate that these exposures are associated with a temporary short-term increase in the risk of acute cardiac events."

The findings were published Wednesday in the journal of the American Medical Association. 


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