So I have been going back and fourth between the elliptical and stair master for my cardio workouts. I usually go for about 30-40 minutes and burn about 450-600 calories, do HIIT a couple times a week as well. Today I thought I was going to go for a long slow cardio session on the sit down bike. I was a little taken back at how hard it kicked my arse and to top it off, according to the machine, I burned a lot less calories.

Is the machine just plain wrong? I thought because of how hard I felt I was working compared to the usual elliptical training I would have burned more calories.

So should I continue to change it up or just stick to the elliptical which according to the machine burns more calories? I know that the calorie counters on these machines are always way off but they are both the same brand so I would assume they should give similar "off" numbers.

Would love some opinions... thanks.

I wouldn't trust those calorie counters...I'd trust a heart rate monitor more. But it does make some sense. Sounds like you were on a recumbent stationary bike. Is that correct? You're not supporting your weight like you do on an elliptical so that right there is going to decrease the calorie burn.

But either way, it does your body good to change things up. Doing the same machine all the time will allow your body a chance to get really efficient at it (which means you'll burn less calories) and also increases your opportunity for a repetitive use injury. Cross training will actuate different muscles making your more well rounded.

When you use an elliptical trainer your whole body is engaged and your working every major muscle group compared to the bike where you are seated and mostly working the legs. You burn a lot more calories on an elliptical machine then on a bike but it is beneficial to change it up every now and then so your body doesn't get to used to the exercise.

Butterthebean is exactly right, your heart rate is your primary guide for determining calories burned. Even though the elliptical is typically a machine that will yield more calories burned, your feelings of working harder is a correct assessment due to the switch up and shock to the muscles. Your muscles are forced to utilize themselves in a matter that is unfamiliar to them--they haven't committed that type of exercise or stress into their "muscle memory." This is why shocking your muscles is so important, whether it's through switching machines, pace, resistance or weight. When muscles have committed an exercise into their memory, they don't work as hard and you don't burn as many calories.