Yeah, there are two things here that will skew your results:
One is how you're determining how many calories you burn. If you're just going by what the number on the treadmill says, then it's most likely not accurate. The only accurate way to determine your calories burned is to know your heart rate while you're working out and then calculate your calories based on heart rate, body weight, time spent, etc.
The second is that the number of calories I might burn or someone else might burn compared to you in 30 mins is going to depend on how high we get OUR heart rates, and our body weight, and so forth.
Also, a third that I just thought of, is that depending on *what* you're doing on the treadmill, the number of calories you burn while in action might not matter. I do a lot of HIIT cardio, rather than ss-cardio, and so I don't burn as many calories during, but HIIT gives you an "afterburn" effect that keeps you burning calories at a higher rate for several hours after you work out.
So really comparing yourself to what others are doing isn't going to give you any kind of baseline to work with. Unfortunately.
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workout/calories burned question
