You know how treadmills, bikes, and elliptical machines have the calorie counters? How accurate is that figure of lost calories?
I can’t specifically comment on the ones you mention, but I know for a fact that the calorie counters on ergometers (rowing machines) are pretty much an outright lie.
As far as I can tell (and my crew coaches information) the counters are based on some sort of mythical “average” human being… though I’ve never heard what specs exactly this “average” person has, or why he loses the calories they claim he’s losing… one of my crew coaches in particular opined that the calorie count had no basis whatsoever in reality
In general, heavier people will burn more calories per unit of exercise, and more out of shape people will obviously be more winded no matter what the calorie counter has to say.
Most modern machines allow you to enter your weight. It seems to me that a stair-stepper would be pretty accurate. If the machine knows how far you’re going up(it doesn’t matter if you’re going up or forcing the machine down), the force of gravity, and your mass, it’s a pretty simple calculation to figure calories needed to do so. However, I cannot comment on the human body’s effeciency in climbing stairs, there may be some inherent losses. Which are probably accounted for by the “mystical average human”, as you note.
I’d say the calculation is accurate, and account for 95% of the work being done. The correction may or may not be accurate, but accounts for less than 5% of the readout. If this is true, the accuracy is 95%+.
Only for an average human being. Variations in biomechanical efficiency, cardiovascular fitness, muscle mass and fat mass throw it off for the rest of us.
With the variation I see, I don’t see how they can all be right. On the elliptical, I can easily “burn” 300 in a half hour; but on the recumbent bikes, I can hardly keep the wheel going fast enough to prevent the machine going into automatic pause, yet I’m lucky to burn 180 in that same time.
At our gym we have several models of elliptical trainers bought over the years. There is variation between how many calories burned they read. I can do 400 calories on one in half an hour, and 500 on the other at maximum effort. I also wonder how accurate the heart rate monitors are on these machines. I have read that some machines count actual calories burned by being on the machine, and other machines include the calories you burn each hour by being awake, plus the extra calories burned on the machine.
Do you think that difference is more than 5% of the total? I have no idea.
I think Mikemike2 is correct as to differences in what the machines are actually calculating. I would want to know how many extra calories I’m burning, the ACBG (actual calories burned gauge) if you will, and not the ACBA, so to speak.
Damn. 
OP here; I too wonder this.
I seem to be around 150-160, according to the machine. Is that per minute? Doesn’t sound accurate to me, but perhaps I’m off base.
Anyone know?
I use a chest-belt based pulse meter, and the figure of 150-160 / min sounds reasonable.
I have no idea how the machine can astimate your pulse rate without a chest-belt, though.
Regarding pulse rate, the “standard” claculation goes: calculate your “maximum pulse rate” using the furmula MPR = 220 - your age (in years)
You should then strive for about 70% of the MPR (depends or the excersice level you want to achieve.
Note that these calculation are rough estimates.