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#1
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Calorie Estimates....
My Cat-Eye cycle computer/ HRM has the option of displaying calorie
expenditure..... This is of interest to me since I cycle to loose weight and I use the information to help calculate my daily calorie balance... Now, obviously as I've cycled regularly for some time I've got fitter. I've noticed a drop in average heart rate over the course I regularly follow.... And a drop in calorie expenditure.... As I've lost weight I've taken to loading the bike with lifiting weights to keep the overall all-up weight the same, or at least within 2-3lb.... But over the same run the calorie expenditure as reported by the HRM is dropping...... May I assume that this is because the HRM is actually calculating the calorie expenditure using time and HR data and NOT taking into account distance speed\time??? As my average heart rate is dropping it's coming up with a lower figure? I suppose it MUST work on some sort of average and make some assumptions since it does not require things like weight or age to be input... If so, how could I more accurately calculate my calorie expenditure... Is there a better HRM on the market that takes these things into aco****??? TIA Matt |
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#2
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Calorie Estimates....
Two factors which will affect calorie expenditu power output (in watts)
and efficiency. That's the bit I don't get... I thought the calorie expenditure would be linked to the amount of work done.... i.e. move a certain weight over a certain distance in a given time..... |
#3
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Calorie Estimates....
On Fri, 16 Jul 2004 13:36:58 +0000 (UTC), LaoFuZhi wrote:
May I assume that this is because the HRM is actually calculating the calorie expenditure using time and HR data and NOT taking into account distance speed\time??? As my average heart rate is dropping it's coming up with a lower figure? I suppose it MUST work on some sort of average and make some assumptions since it does not require things like weight or age to be input... Your assumption is correct. The HRM is using your HR as a proxy for your power output and this, using a suitable conversion function integrated over the time exercised, gives the energy consumed. Your average HR falls as you get fitter so you use less energy for the same task. If so, how could I more accurately calculate my calorie expenditure... Is there a better HRM on the market that takes these things into aco****??? Speed isn't going to be a useful indicator of energy consumption. (What if you're going downhill, uphill, into wind, against wind? You could have the same speed in all these circumstances but I'm sure you'd agree that your energy consumption would vary substantially.) Basic Polar HRMs (probably others too) using OwnCal require weight and gender input, suggesting a more complex algorithm than your Cateye. Top of the range Polar HRMs are more sophisticated again. Given the indirect way HRMs measure energy consumption it doesn't seem reasonable to assume that they are very accurate. See the following link for further information. http://www.howtobefit.com/ehr6.htm -- Michael MacClancy Random putdown - "They never open their mouths without subtracting from the sum of human knowledge." - Thomas Brackett Reed www.macclancy.demon.co.uk www.macclancy.co.uk |
#4
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Calorie Estimates....
On Fri, 16 Jul 2004 15:19:56 +0000 (UTC), LaoFuZhi wrote:
Two factors which will affect calorie expenditu power output (in watts) and efficiency. That's the bit I don't get... I thought the calorie expenditure would be linked to the amount of work done.... i.e. move a certain weight over a certain distance in a given time..... But when you getter fitter you get more efficient, meaning you need less energy to perform this task. Another point is that weight isn't much of a factor when cycling on the (relative) flat. Which is why many people don't bother about saving every last ounce in weight on their bikes. Weight is only an issue when climbing (i.e. when doing work against gravity). The energy you consume cycling mostly goes into overcoming air resistance (by far the largest part) and rolling resistance. -- Michael MacClancy Random putdown - "He is not only dull himself, he is the cause of dullness in others." -Samuel Johnson www.macclancy.demon.co.uk www.macclancy.co.uk |
#5
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Calorie Estimates....
Michael MacClancy writes:
On Fri, 16 Jul 2004 15:19:56 +0000 (UTC), LaoFuZhi wrote: Two factors which will affect calorie expenditu power output (in watts) and efficiency. That's the bit I don't get... I thought the calorie expenditure would be linked to the amount of work done.... i.e. move a certain weight over a certain distance in a given time..... But when you getter fitter you get more efficient, meaning you need less energy to perform this task. No, I'd say the main advantage in getting fitter is that you can expend more energy at a given task, although possibly there is an increase in efficiency as well. A |
#6
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Calorie Estimates....
Basic Polar HRMs (probably others too) using OwnCal require weight and gender input, suggesting a more complex algorithm than your Cateye. Top of the range Polar HRMs are more sophisticated again. Given the indirect way HRMs measure energy consumption it doesn't seem reasonable to assume that they are very accurate. See the following link for further information. http://www.howtobefit.com/ehr6.htm Thanks for the input Michael and the link..... I had wondered about the accuracy of these things. A cheap HRM watch I have gives me roughly double the figure the cat-eye does (it responds to the cat-eye's belt, so it's getting the same data). The route I do (daily at the moment) is 8miles out and return... The out leg is a moderate climb (a bit of a struggle for me) and I try to 'sprint' (says he tongue firmly in cheek) as hard as I can back down on the return.... Conditions are such that I'm often cycling uphill into the wind (and of course getting blown gently along on the way down) I'm deliberately using a very heavy bike 'clonky' and have even gone so far as to compensate for my own weight-loss by filling the carrier with training weights... All up weight is 240lbs.... According to the cat-eye I burn 314 calories on the round trip; down from 345 in the past three weeks.... Seems like a very low figure to me..... |
#7
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Calorie Estimates....
Another point is that weight isn't much of a factor when cycling on the (relative) flat. Which is why many people don't bother about saving every last ounce in weight on their bikes. Weight is only an issue when climbing (i.e. when doing work against gravity). One of the reasons I've weighted the bike; I live at the foot of the Pentlands.... |
#8
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Calorie Estimates....
No, I'd say the main advantage in getting fitter is that you can expend more energy at a given task, although possibly there is an increase in efficiency as well. I must admit I do feel the benefit and find that even on my overweight clonker I'm riding faster and able to push harder. In fact I'm at the point now where I need to think about raising the gearing on the bike, it's granny ring now showing signs of rust on it's wearing edges! But actually probably the main advantages are a clearer head, more energy for day-to-day tasks, improvement in my asthma (which was pretty bad), increase in general strength etc etc... And I look rather less like Mr Blobby than I used to! |
#9
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Calorie Estimates....
If you're losing weight then all other things being equal you'll burn less calories during a given ride as time goes by too. I caught onto that one early and started weighting the bike to keep the overall weight more or less even.. |
#10
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Calorie Estimates....
"Will H" writes:
As you become fitter, your heart rate will be lower for any given wattage and so the calorie expenditure will fall. If you're losing weight then all other things being equal you'll burn less calories during a given ride as time goes by too. |
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