A study published Tuesday in the Journal of the American Medical Association (JAMA) is certainly grabbing the headlines this morning, and, from the headlines alone, it’s easy to see why:
Before anybody panics, however, I recommend reading the study’s fine print. Yes, this study — actually, a meta-analysis review of 14 different studies — did find an increased relative risk of heart attacks among people unaccustomed to regular physical (including sexual) activity.
But the absolute risk — the chance that any sedentary individual will have a heart attack after a particular sudden burst of physical activity (including a, um, roll in the hay) — was very, very low.
Furthermore, the relative risk fell substantially as people increased their regular physical activity.
Here are the details: For this JAMA study, a team of Boston researchers examined the results of 14 different studies that had produced findings regarding the risk of episodic (infrequent) physical and sexual activity on heart attacks, including death from heart attacks. Most of the people in the studies were men between the ages of 55 and 64.
Determining risk for infrequent activities is difficult because the activities are, well, so infrequent. But the researchers determined from these 14 studies that episodic physical activity (exercise and/or sex) was associated with a more than threefold increase in the relative risk of having a heart attack. It was also associated with an almost fivefold increase in the risk of dying from a heart attack.
The absolute risk — the one that really counts — was very low, however. The study found that for every 10,000 person-years represented in the study, two to three people experienced a heart attack and one person died from a heart attack after an episodic burst of physical or sexual activity.
(A person-year represents one person followed for one year. It’s a statistical measurement tool used in these kinds of studies when the population at risk is being observed over varying amounts of time.)
The study also found that the relative risk of having a heart attack triggered by a sudden burst of physical activity fell by about 45 percent for each additional time a person exercised weekly.
So, what’s the take-home message?
First, if these findings prove to be accurate (and I’m not sure how a study could be designed to prove this issue one way or the other), there is a very, very small chance that sedentary people might experience a heart attack if they engage in sporadic physical, including sexual, activity.
But, people can reduce even that risk by staying physically active.
“[I]ndividuals with higher habitual activity levels [experienced] much smaller increases in risk compared with individuals with low activity levels,” the study’s authors conclude. “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.”
So no one should stop exercising (or having sex) because of this study — or because of any alarmist headlines.