The issue of sex as exercise, however, has remained largely unexplored. “There are these myths,” including that sex burns at least 100 calories per session, said Antony D. Karelis, a professor of exercise science at the University of Quebec at Montreal who undertook a study, published in PLOS One in October, to look at how much energy is actually exerted during sex. “But nobody had tested” those assumptions.
To do so, Karelis and his colleagues recruited 21 young heterosexual committed couples from the local area and had them jog on treadmills for 30 minutes, while researchers monitored their energy expenditure and other metrics, in order to provide a comparison for the physical demands of sex. The scientists next gave their volunteers unobtrusive armband activity monitors that gauge exertion in terms of calories and METs, or metabolic equivalent of task, a physiological measure comparing an activity to sitting perfectly still, which is a 1-MET task. Then the scientists sent the couples home, instructing them to complete at least one sex act a week for a month while wearing the armbands, and to fill out questionnaires about how each session made them feel, physically and psychologically, especially compared with running on the treadmill.
When the researchers analyzed all of the resulting data, it was clear, Karelis said, that sex qualified as “moderate exercise,”
Over all, the data reveal that “sex can be considered, at times, a significant exercise,” Karelis said, worth encouraging in people who otherwise balk at working out. Ninety-eight percent of Karelis’s volunteers reported that sex felt more fun than jogging. The other 2 percent, I suspect, will be back in the dating market soon.