Calorie Estimates....

Two factors which will affect calorie expenditure: power output (in watts)
and efficiency.

Power by can be estimated if you know speed, rate of climb and weight of a
rider (and you can make assumptions about wind resistance, rolling
resistance and bike weight).

The efficiency is inferred by the heart rate for any given wattage of power.

As you become fitter, your heart rate will be lower for any given wattage
and so the calorie expenditure will fall.

As to the method of calculating it with an HRM, someone else will have to
answer that.

============
"LaoFuZhi" <the.real.address [email hidden]
thing.not.too.hard.to.work.out> wrote in message
news:[email hidden]...

Quoted message said:

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

Quoted message said:

I've cycled regularly for some time I've got fitter. I've noticed a drop

in

Quoted message said:

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

Quoted message said:

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 acocunt???

TIA
Matt

Quoted message said:

Two factors which will affect calorie expenditure: 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.....

LaoFuZhi said:

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.

Quoted message said:

If so, how could I more accurately calculate my calorie expenditure... Is
there a better HRM on the market that takes these things into acocunt???

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

LaoFuZhi said:

Quoted message said:

Two factors which will affect calorie expenditure: 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

Michael MacClancy said:

LaoFuZhi said:

Quoted message said:

Two factors which will affect calorie expenditure: 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

Quoted message said:

Basic Polar HRMs (probably others too) using OwnCal require weight and
gender input, suggesting a more complex algorithm than your Cateye. Top

of

Quoted message said:

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.....

Quoted message said:

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

Quoted message said:

(i.e. when doing work against gravity).

One of the reasons I've weighted the bike; I live at the foot of the
Pentlands....

Quoted message said:

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!

Quoted message said:

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..

Will H said:

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.

Ambrose Nankivell said:

Michael MacClancy said:

LaoFuZhi said:

> Two factors which will affect calorie expenditure: 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

Ambrose, I'm sure you're right and my initial logic was wrong. Increasing
fitness probably means increasing the body's capacity to do work by
providing more oxygen and consuming more calories.

This means that the calorie consumption algorithms used by most HRMs can
only be rough guides. They must be based on population statistics and are
not specific to individuals. If you start a training programme and a
particular task takes, say, 10mins at an average 120bpm and after a while
you get to do the same task in 10mins at 110bpm then you're going to
consume the same calories because it's the same work. The difference is
that the heart capacity has increased and it can provide the necessary
oxygen to burn the calories at a lower bpm. The HRM doesn't know this
though and measures a lower calorie consumption than actually incurred.

--
Michael MacClancy
Random putdown - "He loves nature in spite of what it did to him." -
Forrest Tucker
www.macclancy.demon.co.uk
www.macclancy.co.uk

Ambrose Nankivell said:

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.

Isn't there a Greg Lamond quote that goes something
like: "It doesn't get easier -- you just get faster"?

--
jc

Remove the -not from email

LaoFuZhi said:

Quoted message said:

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..

Did you keep your weight setting the same in the HRM? The HRM will know
nothing about the weight you put on the bike...

--
Chris

Quoted message said:

Did you keep your weight setting the same in the HRM? The HRM will know
nothing about the weight you put on the bike...

There's no input for things like weight, age, sex etc.......

That's where I'm confused......

Am I expending the same amount of calories, but the HRM isn't compensating
for the reduction in time ( I'm getting faster over the distance) and lower
overall heart rate???

Quoted message said:

You shouldn't put too much stock in the calorie estimates HRM gizmo
produce. You could always ask the manufacturers of yours how it
calculates calories expended. (My polar s520 does have
weight/height/sex data in it - but I don't know exactly how it uses
this.)

yeah, I'm beginning to realise that. Thing is I need some sort of esttimate
and am now baffled by whether I'm using less energy as I get fitter or not..

LaoFuZhi' the.real.address thing.not.too.hard.to.work.out said:

Quoted message said:

Did you keep your weight setting the same in the HRM? The HRM will know
nothing about the weight you put on the bike...

There's no input for things like weight, age, sex etc.......

That's where I'm confused......

Am I expending the same amount of calories, but the HRM isn't compensating
for the reduction in time ( I'm getting faster over the distance) and lower
overall heart rate???

You shouldn't put too much stock in the calorie estimates HRM gizmo
produce. You could always ask the manufacturers of yours how it
calculates calories expended. (My polar s520 does have
weight/height/sex data in it - but I don't know exactly how it uses
this.)

Ambrose Nankivell:

Quoted message said:

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.

As Greg Lemond says, and I love to quote: "It doesn't get easier, you just
go faster."

d.

Jeremy Collins:

Quoted message said:

Isn't there a Greg Lamond quote that goes something
like: "It doesn't get easier -- you just get faster"?

You know, I really should read other people's replies before posting my own.

d.

On Fri, 16 Jul 2004 21:20:08 +0000 (UTC), "LaoFuZhi" <the.real.address
[email hidden] thing.not.too.hard.to.work.out>
wrote (more or less):

Quoted message said:

Quoted message said:

You shouldn't put too much stock in the calorie estimates HRM gizmo
produce. You could always ask the manufacturers of yours how it
calculates calories expended. (My polar s520 does have
weight/height/sex data in it - but I don't know exactly how it uses
this.)

yeah, I'm beginning to realise that. Thing is I need some sort of esttimate
and am now baffled by whether I'm using less energy as I get fitter or not..

If you're hauling the same mass about as you used to be, but at higher
speeds, then you're using more energy. (Acceleration effort is
greater, rolling resistance once you get up to speed is greater, air
resistance is greater)

If you're hauling the same mass at the same speeds, you're using the
same energy.

etc...

--
Cheers,
Euan
Gawnsoft: http://www.gawnsoft.co.sr
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Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk