I don't thing you burn calories at the same rate at every speed. The reason is bionmechanics. Running should be more efficient than walking at a given speed. Perhaps this is about 4 mph which is why the manufacturer changed the calorie burning rate at that point. I am not saying that's what they did, but its a possibility.
So you see it worked! Just look at all the calories you burned testing the machines. It was actually a well thought out design to get you to burn calories. I see though, that you did not use the seconnd or advanced feature of testing all the machines getting inter-machine comparison data.
Anandy, the whole point of numbers that "look good" is to sell a feeling, which is a real money maker. Things don't need to be right, they just have to look good, and those who have no technical background will believe anything that pops up on a display, if the display style isw attractive enough. The fact that the numbers don't mean much is not really so much a design flaw as it is a marketing thing: for "X" dollars burn this many calories. As long as they don't mention snake oil they can still use it, and folks will be happy to pay. Except for those who spot the discrepancies.
You're absolutely right that watt-hours would be a much more accurate method of tracking, Willaim K. I actually used to see a watt-hours display on some machines in my gym, but no longer. Watt-hours seems to have gone away as a measure, largely because most users don't understand them. The result is the numbers get translated to calories burned, which are a measure pertaining to the individual, and therefore involve too many variables, as readers have pointed out here.
@ Charles Murray, if energy expenditure formulas on these machines are flawed and meaningless, then what's the point in making something like this? If we look at the number of such machines around and take into consideration how many people rely on these for their fitness, it seems ridiculous that there is no standardization for these machines.
@ bobjengr, well this is not error, this is blunder on part of manufacturer. It doesn't really matter if the problem lies with the sensor or the software but I suggest it must be something wrong with the software. Sensors as pieces of hardware may falter individually in sensing and displaying. There is little possibility that one kind of sensors are errant.
I could never rationalize paying money to use a gym, when my daily routine usually provides adequate exercise. But now it seems that if one is going to use those machines then the display should show the power delivered, which they might be able to sell to the utilities, or at least be able to use to power the building. Dispaying watt-hours would be a more worthwhile display and also much easier to determine with good accuracy. Calories burned depends a bit on who is exercising, those who are quite fit can do the same thing and burn less, because they do it more efficiently. And probably that calculator in the machine is not able to handle that variable term. I would not be inclined to believe any of those numbers without being able to see the algorithm and formulas used to produce them. Otherwise they should be regarded as just so much "sunshine".
So you think calculating calories burned in a biological system is that simple? All the machines are just giving numbers based on some "average" user for which there is no standard. In order to really know for yourself, you need to also measure heart rate and oxygen consumption. Even if you trian with a heart rate monitor to keep that variable under control, it will also vary depending on what type of activity you are doing and what you have been eating. So it is best just not to worrry too much about calories burned and set perfomance based goals instead.
@ Imkmet88, you have certainly made some interesting points but these are confusing at the same time. First, I couldn't decide whether you are just suggesting that it might be the case or you are sure that this is the case. Secondly, general view is that jogging or running burns more calories than walking or briskly walking. Is it the other way round actually?
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