Weird Science tries to count its calories during Jurassic sex

You know what would be more fun than this? Anything. But sex in particular.

Taking performance monitoring into the bedroom. Everybody likes to know how much they're getting out of their exercise: we use cycling computers and pedometers, and exercise machines read out what's happening down to the last Watt. It's probably a safe bet that some people were tracking their exertion in the bedroom down to the calorie, but a handful of researchers decided to save the rest of us from having to do so by getting 21 couples to agree to wear devices that would track the energy they used from the onset of foreplay to the end of intercourse (with at least one partner having had an orgasm).

The result? Sex is pretty good exercise, comparable in some cases to a moderate workout on a treadmill. And, better yet, "almost all of the participants reported that sexual activity was more pleasant than the treadmill exercise." Men burned a bit more than women (4.2 kCal/minute vs. 3.1 kCal). And remember, this started with foreplay—it's likely that the actual sex was even more energetic.

The authors missed out on a great opportunity to correlate calories burned with pleasure, since they asked all participants to rate their own and their partner's apparent enjoyment. Nobody rated either of these as low (which makes me wonder about exercise experience of the few exceptions to the "more fun than a treadmill" ratings). And the exact same percentage of men and women rated their pleasure as high. The difference is that both sexes think the men enjoy it more. As a result, men underestimate their partner's enjoyment; women overestimate it.