Researchers from Montreal's University of Quebec enlisted 21 heterosexual couples ages 18 to 35 for the study, and asked them to wear the fitness tracker SenseWear. Each subject first completed a 30-minute jog on a treadmill to provide a baseline measure of their calorie expenditure, and then they were sent home with the armbands and instructions to have sex while wearing the sensors.
Most sex sessions lasted around 25 minutes (with some as short as 10 minutes, others almost reaching an hour), with men expending more energy than women. On average, men burned 101 calories when having sex, and women burned 69 calories. Still, that didn't beat the calorie burn when jogging: men burned 276 calories, or 9.2 per minute, while women burned 213 calories, or 7.1 per minute.
A separate study published earlier this year, however, offers a different conclusion, finding that sex only burns 21 calories on average. David Allison, a biostatistician at the University of Alabama at Birmingham, tested the, sexercise, theory -- that sex can be exercise -- but found that sex lasted only six minutes on average, burning a paltry 20 or so calories. The findings were published in February in New England Journal of Medicine.