Question: how many calories does running a mile in 9 minutes burn?
Answer: At 6.7 mph (or a 9-minute mile), they'll burn 409 calories, and at 7.5 mph (an 8-minute mile pace), they'll burn 465 calories. To double your calorie burn per mile, you'd have to literally cut more than four minutes off your pace, which is a huge amount of time.