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Calorie Estimates....



 
 
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  #1  
Old July 16th 04, 02:36 PM
LaoFuZhi
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Default 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  
Old July 16th 04, 04:19 PM
LaoFuZhi
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Default 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  
Old July 16th 04, 04:28 PM
Michael MacClancy
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Default 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  
Old July 16th 04, 04:41 PM
Michael MacClancy
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Default 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  
Old July 16th 04, 04:51 PM
Ambrose Nankivell
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Default 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  
Old July 16th 04, 04:56 PM
LaoFuZhi
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Default 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  
Old July 16th 04, 05:01 PM
LaoFuZhi
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Default 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  
Old July 16th 04, 05:05 PM
LaoFuZhi
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Default 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  
Old July 16th 04, 05:29 PM
LaoFuZhi
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Default 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  
Old July 16th 04, 06:07 PM
Paul Rudin
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Default 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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