On most of the cardio machines at the gym (treadmills, elliptical trainers, bikes, etc.), there are automated displays that supposedly calculate how many calories you’re burning doing whichever activity. Some of them are more sophisticated than others, where they’ll ask for weight/age/sex before you start your program. Others don’t ask you any of that, they just spit out a running total as you go.
I’d think that the ones that ask for your weight/age/sex are more accurate than those that just calculate based on an average calories burned/min, but even with the weight/age/sex data, just how accurate are these things? Does it depend on current fitness level? I mean, if two people of the same height/weight/age/sex were to get on the same machine for the same length of time, but one person has been sitting on the sofa for a year and the other person has been going to the gym 5x a week for a year…the one who’s less fit is probably going to have a heart rate through the roof while the more fit person will be able to do the time with no problem. Given that all the machine knows is that they’re the same weight/sex/age, which person is the calories burned output more accurate for, the fitter person or the less fit person?
I know that my example above makes a lot of assumptions (i.e. that both people maintain the same pace, etc.)…but in general, what sort of person is the “calories burned” based on?
I have read that they are not particularly accurate, not necessarily because the calculations they do are not correct, but because the measurements they make that feed into the calculations are not usually very well calibrated. The article I saw suggested that the best way to rate the effectiveness of your work out is to track your heart rate (but don’t use the built-in contact HRMs that some machines had, as they are also not very accurate.)
No cites, sorry. I don’t even remember where I saw it.
Well, let me put it this way; they may be as accurate as you please when they come out fo the factory, unless those things are being regularly recalibrated by a legitimate calibration firm, you can’t even trust that it’s measuring your speed or heart rate correctly. A measurement device subjected to that level of use that is not regularly recalibrated is useless.
I am very skeptical of their accuracy in any regard.
OK, so assume they’re not being calibrated regularly (which doesn’t really answer my question about who they’re accurate for when they are calibrated, but I’m willing to go off on this tangent)…how much are we talking? If it says I burned 500 calories, is it possible that I’ve really burned 100? 400? 550? 1000?
Aside from the calibration, there are a few other reasons why those calorie counters aren’t worth much.
Picture two 5’10", 200 pound men. The first is a marathon runner, at about 12% bodyfat. The second is a couch potato, at about 25% bodyfat. According to the calorie counter, they’ll both burn the same amount of calories. Does that sound at all realistic?
I’m a little confused, ultrafilter. Is the marathon runner is more efficient so that he therefore uses fewer calories?
Because, why wouldn’t they burn roughly the same amount of calories if they do the same mile on the treadmill?
When the get off the treadmill, the couch potato is going to look a hell of a lot worse for the wear, but do calories <=> effort expended <=> percieved difficulty of exercise?
Or is it exactly the opposite, that the marathon runner has a higher metabolism and would burn more calories?
It’s not obvious to me why they would burn different amount of calories, or who would burn more.
I guess I’m thinking of it from a physics perspective. Say couch potato and mathon runner are going to climb a hill. CP and MR weigh the same. They therefore need to make the same change in their potential energy. From a physics point of view, they both need to expend the same amount of calories. Is there some key biological element to this that I’m completely missing?
Yes. The marathon runner will burn fewer calories because his body has adapted to run long distances with a lower energy expenditure.
The major adaptations are an increase in capillary density (allowing food to reach the cells faster), an increase in mitochondria counts (more energy production from food), and an increase in intramuscular fat (a convenient energy source).
This is one of those pieces of common wisdom that’s a little too common and not quite wise enough. Heart rate is only a useful measurement because it correlates well with oxygen uptake, which is the best measure of how hard you’re working in aerobic exercise (and is fairly hard to measure directly). Max oxygen uptake is the single best indicator* of cardiovascular fitness.
Why? Well, during long-term exercise, glycogen stores get low, and protein’s not that great an energy source (although it is used), so the body has a preference for fat. But fat can’t be burned until it’s removed from fat cells, in a process that requires oxygen. In fact, the amount of oxygen available really determines how much fat can be burnt. The more oxygen you can take in, the more fat you can burn, both while exercising and while at rest.
This is important because, unless you’re running a marathon or training for one, it’s extremely hard to burn a lot of calories/fat through exercise. The key is to find the types of exercise that will have the greatest effect on your resting metabolism. Heavy weightlifting and interval training are the best out there.
Any of these programs will help immensely, although you do have to actually do them. I like the last one, but play around and see what you think.
btw, as a group, cross-country skiers have the highest max oxygen uptake of any endurance athletes, so you might want to use a cross-trainer if you’re going to use a machine.
The calorie counters are pretty approximate. Just try three similar but different machines and you’ll see the numbers vary quite a lot. Also, you might well feel more tired after doing the supposedly least strenuous workout.
I strongly disagree, as a person who has done aerobic exercises routinely for years. Aerobic exrecise, combined with limited caloric intake, is a very good way to burn calories and fat. I know from experience.
The calorie meters are not very accurate, but they are good enough for their purpose.
If you are a normal person trying to lose weight and stay fit, they give a good estimation of how many calories you’re using.
If you are some performance athlete where you have to burn exactly 240 calories because that’s how many were in the Snicker’s bar you ate but weren’t supposed to, well, the machines aren’t very good for that.
The only way to accurately measure the calories you personally burn doing an activity would be to hook you up to an oxygen-sensing machine that would monitor your breath.
I also use the calorie meter to get a sense of how hard I’ll have to work out to burn food off. So if I’m looking at a Snicker’s bar and I know that it takes me about 15 minutes to burn the 240 calories it has, I get a sense of how long I’ll have to work out to burn it off. Is it exactly 15 minutes? No, but it is about 15 minutes which is all I need to know.
There’s also the Post-Exercise-Caloric-Expenditure which is not shown by the calorie meters. The PECE is the extra calories your body burns in recovery after strenuous exercise is over. In a strenuous workout, the PECE can be an extra 50% of the calories you burned while working out. So do a hard 600 calorie workout and burn an extra 300 bonus calories after the workout.
And where did I say that it’s not? All I said is that it’s difficult, not impossible.
You’ll note also that I said nothing about caloric intake. A low intake along with aerobic exercise is a good way to lose weight (although it’s not muscle sparing, which is bad as you get older), but aerobic exercise alone isn’t enough.
Of course, you have to watch your diet no matter what you do. But it’s just smart to take advantage of any effect that raises your resting metabolism, as no matter what, you’re going to spend more time resting than exercising.
But those two adaptations (and others such as greater respiratory capacity) are things that make it easier to burn more energy and have nothing to do with efficiency. It could well be that there are adaptations to make the marathoner be more efficient–I would expect there are–just not the ones mentioned. On the other hand, it is entirely possible that the marathoner has a higher basal metabolism. One thing I can do is measure my own pulse and compare it to the HRM. I would have thought that that was one thing about which there could not be much to go wrong, so long as the internal clock is right (which it is since I can compare the elapsed time to the clock on the wall).
