Madonna was framed in Body of Evidence. It's super hard to kill somebody with sex.

In the 1993 "erotic thriller" (everyone's favorite kind of thriller) Body of Evidence, Rebecca Carlson, played by Madonna, is taken to court for murder. Specifically, she's accused of having had rough or aggressive sex with a series of older rich men in order to cause their deaths. One survivor even says that she ended their relationship after he had heart surgery that made him healthier. Minor spoiler alert: she testifies on her own behalf and is eventually acquitted.

But her attorney, who she's been having rough sex with (natch), sneaks to her house after the trial and finds her with the doctor of one of her victims. The doc has coached her in how to kill men with sex. She taunts the doctor, who she's also been having sex with (natch), about how she can get him to do anything because of her world-class bedroom skills. When she tells him to get lost, he flies into a rage, eventually shoots her, and she falls out a window. I think there was some wrassling between the doctor and the lawyer in there somewhere. Aaaaaaaaand scene. At least that's how I remember it. I also remember some candle wax early in the movie, but I don't think it applies to the point I'm about to make. 

In a brand-new research letter in JACC (paywalled and not indexed by pubmed as of this writing), investigators studied 4557 cases of sudden cardiac arrest in or around Portland, Oregon, area between 2002 and 2015. Did I mention that Body of Evidence was set in Portland? Because it was. The mean age of the men was 65 years, which is prime Carlson Country, too.

They found that far less than <1% of cardiac arrest cases were linked to sex (34/4557, for an incidence of 0.28 per 100,000 adults per year). In 18 cases, the arrest occurred during sex. In 15, it was right after, and in one, the timing could not be determined. Only 1/3 of the people who had sex-associated cardiac arrests had any kind of bystander CPR. That's a hallmark of Rebecca Carlson if I've ever seen one. Also in the Rebecca Carlson tradition: almost 95% (32/24) of the sex-related cardiac arrests happened in men. The likelihood of a history of heart failure or heart disease was the same in sex-related and non-sex-related arrests. But men who had sex-associated arrests were on average five years younger than the non-sex-associated arrests. They were slightly more likely to be African-American, too. They note that an autopsy study in Germany came up with slightly higher risk, at around 0.2% of cases linked to sex.

So women: have all the high-intensity sex you want. You're safe. Men: If you're willing to roll the dice on your own personal Rebecca Carlson, the die is probably 100-sided, and you only die if it lands on the 100. Proceed accordingly. 

Are triathlons dangerous?

First things first: I've never done a triathlon. I swim like a St. Bernard. But I've done a lot of endurance bike racing, and I've been at more than one event with a death, the most recent the 2017 Dirty Kanza. So I was interested that in the latest Annals of Internal Medicine, investigators looked into a sudden death database to identify 135 race-related deaths and cardiac arrests in American triathlons between 1985 and 2016. Interestingly, right at two-thirds of deaths and arrests happened in the swim part of races, which usually comes first, before the bike and run. The editorialists spend a lot of energy trying to link swimming to some special form of stress from cold water or other factors that might be extra-dangerous. But to me, the swimming link seems consistent with the finding that in autopsies, about half of subjects had cardiovascular abnormalities, most often old-fashioned atherosclerotic disease. Swimming caught most of these people simply because it was the first event. Had running or cycling come first, I suspect one of them might have been the death leader. I'm not convinced by their observation that most marathoners die toward the end of races; anyone who's seen the scrum at the beginning of a triathlon knows that it's inherently different than the often walking pace seen at the start of a marathon: 

From http://www.zwemza.com/?p=5515, triathletes tempting fate. 

85% of victims were male, but I'm not sure the significance of that number, since >60% of participants (at least in pro Ironman races) are male:

From https://www.outsideonline.com/1964906/fight-gender-equality-ironman

And if you look at total Ironman competitors, the distribution of sex comes much closer to the death/cardiac arrest statistics:

But sex aside, we're forced to see that cardiac arrest and death are not rare among triathletes. Between 2006 and 2016, their incidence was 1.74 per 100,000 participants in the study. The risk of death increased with increasing age, unsurprisingly. Don't let this dissuade you from being more active. The benefits of physical activity far, far outweigh the risks in almost everyone. If you're inactive now and thinking of becoming active, or if you're active now and thinking of doing really hard-core things like triathlon, consider taking the American College of Sports Medicine's new-ish algorithm to your doctor and talking it over before you hit it really hard:

We don't know how really weird stuff like performance enhancing drugs effects this. My suspicion is that it's not good.