'Episodic' Physical and Sexual Activity Linked to CV Risk

Shelley Wood

March 24, 2011

March 24, 2011 (Boston, Massachusetts) — It's a perennially sexy topic: just what are the cardiovascular risks of "episodic" physical and sexual activity, especially for the habitually inactive? A new literature review and meta-analysis published in the March 23, 2011 issue of the Journal of the American Medical Association provides some new numbers that authors say may be of use to patients and physicians going forward--providing they understand just what they mean [1].

Dr Issa J Dahabreh and Jessica K Paulus (Tufts University, Boston, MA) used a complex, multitiered study design to get at the issue of whether the risk of myocardial infarction (MI) or sudden cardiac death was elevated during or shortly after an episode of physical or sexual activity--not an easy thing to measure, they say, because "exposure" to these events is infrequent and transient. Using a literature review, the authors found 14 studies: one study addressed the impact of both types of activity on cardiovascular risk, 10 focused solely on episodic physical activity, and three looked only at sexual activity.

By Dahabreh's own admission, their analysis is complicated, but not novel--by definition, a meta-analysis of previous case-crossover studies means that others have already addressed the very questions that he and Paulus were hoping to answer--namely, the question of cardiovascular risks associated with physical or sexual activity. But by combining multiple studies, he told heartwire , their analysis brings more "precision" and statistical power to the findings and provides "additional insights"--helping "discern patterns that are not possible to identify by looking at a single study."

Risk of Cardiac Events Occurring During/After Activity

For example, they write, episodic physical activity across multiple studies was associated with almost a 3.5-fold increased risk of MI and a nearly fivefold increase in the risk of sudden cardiac death. Episodic sexual activity was associated with 2.7-fold increased risk of MI.

These numbers speak to a relative risk "of a large magnitude," Dahabreh acknowledged, but he stressed that it is important to understand just what is being evaluated. He's worried that the media attention this paper has aroused may focus only on the sexual-activity component and may lead to confusion over the paper's findings.

"What is being compared here is the probability of being exposed to physical or sexual activity within a few hours of experiencing the heart attack, compared with control periods. This is a matched-case design only, so one would not interpret this by saying that there is a 3.5-fold increase in risk for people who exercise. Instead, the interpretation would be, for example, for physical activity and heart attack, that there is a 3.5-times increase in risk while the individual is exercising or immediately after physical activity, compared with control periods when the individual is not engaged in physical activity."

For any given person, Dahabreh stressed, the absolute risk was very small: the absolute risk increase associated with one hour of additional sexual or physical activity per week was 1 per 10 000 person-years for sudden cardiac death and 2 to 3 per 10 000 person-years for MI.

But of note, risk of both MI and sudden death fell dramatically if individuals reported engaging in some kind of habitual physical activity. For each additional instance of increased physical activity performed per week, risk of sudden cardiac death decreased by almost one-third, while risk of MI decreased by approximately 45%.

"You Need to Be Constantly Physically Active"

Dr Eileen Handberg (University of Florida, Gainesville), asked to comment on the study for heartwire , said that it confirms what most people already believe to be the case.

"I think this paper is going to get a lot of [media] play, but I'm not sure that this is anything more than what has already been said--that, basically, if you're not in good shape, and if you try suddenly to be active, then you put yourself at risk. And whether that physical activity is walking, running, shoveling snow, or having sex, you're at some risk," she said. "You really need to be constantly physically active, and you need to start that as a child, and you need to carry it through until you're 90."

Dahabreh, however, points out that one of the novel aspects of this paper is that it gives physicians and patients "more precise numbers--we put a number on the association." Those numbers, he said, may perhaps help inform future updates of guidelines on how to advise patients on the safety of physical and sexual activity.

He also stressed, however, that the message from the paper is not that people can go out and increase their level of physical (or sexual) activity in order to reduce risk of sudden cardiac events.

"This is a little bit more nuanced, I feel. We definitely found that people who have higher levels of habitual physical activity experienced less of an increase in risk while [engaging in] physical activity both for MI and sudden cardiac death; however, we cannot really make the causal claim, based solely on our data, that habitual activity levels protect from the triggering effect. The reason for this may be that habitual activity may be a marker for good health status of a generally fit individual."

The authors had nothing to disclose.