Nice link but assuming people burn 450+ calories in less than 40 minutes of exercise is pretty stupid for most people. The fact they used 30-45 minutes lets me know they have no fucking clue. It can be done but most times it is a no. I'm a 6ft 7 man and I sometimes run for about 90 minutes without long breaks. In that time I burn less than 450ish calories in 40 minutes of running without a major pause. (I define major as anything more than 5 minutes) And that is running: a very high intense workout with little to no breaks. Average people burn about 200-400 cal an hour at the gym depending on their level of intensity. I'm not even gonna talk about women. I mean, I am like 200 pounds at 6ft 7 and I can barely hit the mark of 450 in that time limit even at my size. A small woman should hope to reach 300s in 40 minutes, with very high intensity.