Do burned calories differ in/out of shape?

xLyric

Person A and Person B are identical in every way, except B is in better shape. Same height, weight, gender otherwise. They do the same exercise for the same amount of time, and in the end A is wheezing and doubled over, proclaiming imminent death, while A barely broke a sweat. Did they burn the same amount of calories?

Ianultrarunner

They would burn at different rates as Person A would likely have a lower maximum heart rate and and higher resting heart rate than Person B but there are many other factors that come into play such as medications and genetics.
The only way to be sure would be for each person to wear a identical Heart Rate Monitor. Never go by what is displayed on a exercise machine.

Azdak

Depends on the exercise. If they are doing consistent workloads--e.g. running @ 6.0 mph--- then the answer is mostly "yes".

If you are doing steady-state aerobic exercise at a measurable workload -- as opposed to, for example an interval workout, group class, etc-- then any workload has a relatively fixed energy cost, regardless of who does it.

There will be a small mechanical advantage (~5%) for a well-conditioned individual with many years of training, and this assumes that the unfit person has at least made this initial adaptation to the workout/workload. But, for the most part, calories burned during cardio exercise depend on 2 factors: workload x body weight.

People who use HRMs often mistakenly believe they burn fewer calories when they become more fit because, for any fixed workload, your HR will decrease as your overall conditioning increases. Thus, the HRMs show fewer calories. But that's because they have not adjusted the HRM settings to account for their increased fitness level. In other words--they are not burning fewer calories (unless they have lost weight), it's just that their HRM settings are outdated.