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Fitness Minutes: (12,611)
3,886 3/31/10 1:02 P
In my humble opinion ...
I think exercising to eat more or justify eating more is a recipe for failure. Maybe failure is too harsh of a word, let's say "unexpected results". I always considered my cardio icing on the cake. Create a calorie deficit on the load side, not the burn side.
Here is one extreme example. I hit the treadmill for 50 minutes the other day. The Polar registered 548 calories but the treadmill registered 780.
I agree that the heart rate or caloric burn is just a good tool to make sure we are exerting ourselves and benefiting from the exercise as much as we can, but some people use those readouts on the machines as gospel and even use it to justify giving themselves a caloric treat as a result. I can just see the calorie estimates doing more harm than good in some cases.
About a year ago, I saw an article discussing the inaccuracy of calories measured with respect to the elliptical machine. The count tends to be 10 -15% higher of what you actually burned. I do about 70 mins of elliptical and get a count of 850.... I just subtract 15% (720) and use that as my official count.
Fitness Minutes: (2,605)
376 3/30/10 2:16 P
Yes, I think the difference is that your HRM takes into account your HR while the machines just count steps,distance...ect and estimate.
I typically burn about 500-550 calories in 30 minutes on the elliptical machine according to my FT7 HRM. It links to the machine but the machine still calculates it out closer to 600-650, sometimes even 700 and it varies from one machine to the next.
Also, keep in mind that you should be updating the weight setting on your HRM everytime you weigh in for the most accurate reading. I've heard of a few people who lost 10-15 but didn't update the HRM weight and this was the cause of higher than expected calories burned numbers.
Your research is correct. Determining calories burned is not a simple calculation. The more information you put in, the more accurate the reading will be but even then, most machines are programmed based on some algorithm that tries to make it a one size fits all type thing and it's not.
You're correct that the algorithm used on most machines does not factor in your heart rate, it's just time/speed/resistance calculation and the heart rate is there to help people stay in a zone while they're working out.
I don't use the read outs as gospel, I use them as a measuring point to determine if I worked as hard on that workout as I did on the last. For example on the elliptical in 30 minutes, it says I burn 525 calories. If the next time I'm on it, I don't burn 525 calories, I either lost weight, or in most cases, I didn't work as hard that time.
I've been meaning to get a chest strap so I can determine how many calories i'm burning while doing p90x but haven't got around to it.
The machines read the Polar chest strap, and I checked several times and the HR is the same on the watch as it is on the machine. I don't think the machines use heart rate in their calorie calculation. At least it seems that way to me.
Fitness Minutes: (29,526)
1,045 3/30/10 10:09 A
The machine is not getting a complete look at your HR either unless it has a way to connect to your HRM strap. (Some can do that) Yes, machines I have seen do over estimate the burn. But thats just it.... it is an estimate!
Fitness Minutes: (2,605)
376 3/29/10 11:56 A
Yes, I do this all of the time. I find it also varies from machine to michine even of the same exact type. Most of the machines are between 25%-35% higher than my Polar FT7 shows. I trust my HRM more than the one on the machines, for sure.
For the past week I have been using both a Polar F6 monitor and the readouts on the cardio machines to compare the calories burned estimation on both.
What I have found is that by far, the machines read 30-40% higher than the HRM does. The machines estimate caloric expenditure by accounting for time and incline/resistance/speed whereas the HRM only uses time and heart rate to calculate. I set the weight, and age on both the same, but only the HRM has a setting for height.
Has anyone else tried this in the past? I was shocked to see how the machines report a much higher burn. Maybe I'm in better shape than the machines assume for someone of my age and weight, and my heart rate is lower than expected at the particular speed and incline of the machine? Who knows.
Interesting results, just thought I would share.
Other interesting points: spin class burns a ton more calories than any cardio machine; an hour of fairly competitive racquetball burns around 800-825 calories on average.
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