A night of hot and heavy sex can end in a lot of heavy breathing. And not in a good way.
A new analysis appears to confirm that sex, like other forms of physical activity, can trigger a heart attack — especially among those who aren't accustomed to the, um, exertion.
The increase in risk is relatively fleeting: a brief "hazard period" lasting about one to two hours during and after the activity.
And, most importantly, the effect is less pronounced among those with high levels of "habitual exertion" who engage in regular physical activity.
Based on a body of work stretching nearly two decades, the analysis found that "episodic sexual activity," or a bout of sex, is associated with a 2.7-fold increased risk of myocardial infarction over a short period of time.
Translation: Making love could land you in the hospital.
Episodic physical activity, meanwhile, was associated with a 3.5-times increased risk of heart attack over one to two hours — as well as an increased risk of sudden cardiac death.
The results mirror those of studies showing that weekend hockey warriors — middle-age adults who play recreational hockey intermittently — are at greater risk of heart attacks because they're not accustomed to the stress on their bodies.
"Acute cardiac events are a major cause of morbidity and mortality, with as many as a million acute myocardial infarctions (heart attacks) and 300,000 cardiac arrests occurring in the United States each year," the authors write in this week's issue of the Journal of the American Medical Association.
More than 75,000 heart attacks occur in Canada each year, according to the Heart and Stroke Foundation.
Despite the known benefits of regular physical activity, "we knew that, at least anecdotally, there is an association between physical activity or sexual activity and heart attacks or sudden cardiac deaths," said lead author Dr. Issa Dahabreh, a research associate at Tufts Medical Center in Boston.
"We were aware of some of the studies that were out there," Dahabreh said.
The team combined the best they could find, summarizing the evidence and looking for patterns.
They analyzed a total of 14 studies that together involved about 6,000 people. Most participants tended to be in their 50s or 60s, and there were more men than women.
The studies looked at what happened in the few hours before a heart attack or sudden cardiac death, and then compared it to a "control" period — for instance, the same hour period in the week before the heart attack occurred.
The analysis found that episodic physical and sexual activity is associated with a statistically significant — albeit short-term — increase in the risk of "acute cardiac events."
"Any effect would likely be the few hours while the individual is exercising or having sex, and maybe one or two hours after," Dahabreh said.
None of the studies looked at the link between sex and sudden cardiac death, only sex and heart attacks.
The studies included diverse physical activities, such as jogging, swimming or climbing stairs.
Overall, the absolute risks were small: For every 10,000 people who exercised an additional hour a week, there would be one to two cases of heart attack or sudden cardiac death per year that could be attributed to physical exertion or sex, said co-author Jessica Paulus, an assistant professor of medicine at Tufts University School of Medicine and an adjunct assistant professor of epidemiology at the Harvard School of Public Health.
What's more, people with higher physical-activity levels experienced a lower — and often no increase in — risk of heart attack.
"Individuals who engage in physical activity several times per week experience a much lower increase in risk while they are exercising, both for heart attack and sudden cardiac death," Dahabreh said.
For each additional time per week that someone was exposed to physical activity, the risk for heart attack decreased by about 45 per cent, and the risk for sudden cardiac death dropped by 30 per cent.
The team didn't look at what's happening physiologically, but exercise increases blood pressure. It also increases the output of adrenalin and other hormones.
They researchers also didn't look at exactly what kind of physical activity may trigger a heart attack.
"Is it jogging? Is it shovelling snow? What specific type of physical activity that's episodic in nature might be the most triggering? That's a question we can't answer from the data we have," Paulus said.
The risk, however, appears to increase with moderate to strenuous physical activity.
Sedentary people who want to start exercising should do so under the guidance of a doctor, and increase the amount of exercise gradually, Paulus said.
People unaccustomed to regular physical activity appear at greatest risk — especially if they're older, male or have other risk factors for heart attack.
"These are the individuals who appear most vulnerable to the triggering effect," Paulus said.
