How Accurate Are Those Monitors, Anyway?

[Prisoner A]

For immediate release from Ye Olde Rambling Question Dep't.:

I'm on some elliptical at the gym, have been doing it 40
minutes three times a week, each session the machine read-out
claims I've lost ~850-900 calories (range due to variable
intensity)...how accurate is that? I find it hard that with 40
minutes of sweat I've burned that many calories. It doesn't
feel too hard, relatively speaking (though I do Level 15 out
of 20 available, with 20 as the hardest).

There's also the heart rate monitor that has me at the upper
celing of my target heart range (which is supposed to be
~142-157 for a 35 y.o.) for almost all 40 minutes, which I
find incredible, too...I definitely look like I'm fit --
Greco-Roman statue and all -- but it all feels much easier
than I'd expected (though there is surely a psychological
component involved, and I've learned fairly well to tune out
unpleasantries like fatigue, etc.), so I'm wondering whether
such devices are trustworthy...how are such numbers
calculated, anyway? On this elliptical, the target heart rate
seems to come from sensors in the handles....

[Mike R.]

"Prisoner at War" <prisoner_at_war@yahoo.com> wrote in
news:1170349029.605054.235430@m58g2000cwm.googlegroups.com:

>
> For immediate release from Ye Olde Rambling Question Dep't.:
>
> I'm on some elliptical at the gym, have been doing it 40
> minutes three times a week, each session the machine
> read-out claims I've lost ~850-900 calories (range due to
> variable intensity)...how accurate is that? I find it hard
> that with 40 minutes of sweat I've burned that many
> calories. It doesn't feel too hard, relatively speaking
> (though I do Level 15 out of 20 available, with 20 as the
> hardest).
>
> There's also the heart rate monitor that has me at the upper
> celing of my target heart range (which is supposed to be
> ~142-157 for a 35 y.o.) for almost all 40 minutes, which I
> find incredible, too...I definitely look like I'm fit --
> Greco-Roman statue and all -- but it all feels much easier
> than I'd expected (though there is surely a psychological
> component involved, and I've learned fairly well to tune out
> unpleasantries like fatigue, etc.), so I'm wondering whether
> such devices are trustworthy...how are such numbers
> calculated, anyway? On this elliptical, the target heart
> rate seems to come from sensors in the handles....

Don't rely on what your heart rate is supposed to be w/ regard
to your age. Just because you are 35 doesn't mean your maximum
heart rate is the same as the typical 35 y.o. I'm 40 and have
at least a 205 bpm HR max. (as indicated in the final sprint
of a 10K race in Nov.) which is 20 bpm higher than what I'm
"supposed" to have. Find a means of testing your HR max. so
that you can determine the appropriate target ranges for you.

mike

--
Posted via a free Usenet account from http://www.teranews.com

[Joeu2004]

On Feb 1, 8:57 am, "Prisoner at War"
<prisoner_at_...@yahoo.com> wrote:
> I'm on some elliptical at the gym, have been doing it 40
> minutes three times a week, each session the machine
> read-out claims I've lost ~850-900 calories (range due to
> variable intensity)...how accurate is that?

Not at all. The machines cannot measure calories burned. They
estimate calories based many assumptions and very little
personal input data (just weight, speed of the machine and
intensity level).

BTW, you misunderstand the number. It says you are burning
that many calories, not "losing" those calories. If you turn
around and eat a hamburger afterward, you probably "replace"
most of those calories. Second,

> There's also the heart rate monitor that has me at the upper
> celing of my target heart range (which is supposed to be
> ~142-157 for a 35 y.o.) for almost all 40 minutes, which I
> find incredible, too [...]. how are such numbers calculated,
> anyway? On this elliptical, the target heart rate seems to
> come from sensors in the handles....

I am not sure what you are asking. How are __what__ numbers
calculated?

Your current heart rate is not "calculated" at all. It is
measured, in your case by the sensors in the handles.
Generally, "hand" (really finger) sensors are not as accurate
as a chest strap. But as long as your hands are moist and
grasping the sensors, they are probably accurate enough.

On the other hand, your target heart range is based on
averages. The THR is a percentage of your max HR. First, it
appears that you or the machine is estimating your MHR with
any one of several age-based formulas. The most common one is
"220 - age". Statistically, there is a 30% chance that your
MHR differs significantly, be it higher or lower. Second, even
if you know your MHR, the percentage at which to exercise
depends on your personal level of fitness. In any case, it is
good to vary your HR throughout the session.

Try sending more time at the high end (157). If that still
feels "earier than expected", try increasing the intensity
(speed or resistance) so that your HR increases in 5-10
increments. You should find a point at which you feel
exhausted after a few minutes. Back down to 142-157 again,
perhaps even lower, for several minutes. Then challenge that
high level again, perhaps slightly lower. Do this repeatedly.

[Skippy]

"Prisoner at War" <prisoner_at_war@yahoo.com> wrote in message
news:1170349029.605054.235430@m58g2000cwm.googlegroups.com...
>
> For immediate release from Ye Olde Rambling Question Dep't.:
>
> I'm on some elliptical at the gym, have been doing it 40
> minutes three times a week, each session the machine
> read-out claims I've lost ~850-900 calories (range due to
> variable intensity)...how accurate is that? I find it hard
> that with 40 minutes of sweat I've burned that many
> calories. It doesn't feel too hard, relatively speaking
> (though I do Level 15 out of 20 available, with 20 as the
> hardest).
>
> There's also the heart rate monitor that has me at the upper
> celing of my target heart range (which is supposed to be
> ~142-157 for a 35 y.o.) for almost all 40 minutes, which I
> find incredible, too...I definitely look like I'm fit --
> Greco-Roman statue and all -- but it all feels much easier
> than I'd expected (though there is surely a psychological
> component involved, and I've learned fairly well to tune out
> unpleasantries like fatigue, etc.), so I'm wondering whether
> such devices are trustworthy...how are such numbers
> calculated, anyway? On this elliptical, the target heart
> rate seems to come from sensors in the handles....
>

The heart rate is likely to be ECG based, and thus quite
accurate.

The calorie counter is guessing based on anything you tell the
machine when you get on (age, weight etc).

Skippy E&OE

[Nash]

"Prisoner at War" <prisoner_at_war@yahoo.com> wrote in message
news:1170349029.605054.235430@m58g2000cwm.googlegroups.com...
>
> For immediate release from Ye Olde Rambling Question Dep't.:
>
> I'm on some elliptical at the gym, have been doing it 40
> minutes three times a week, each session the machine
> read-out claims I've lost ~850-900 calories (range due to
> variable intensity)...how accurate is that? I find it hard
> that with 40 minutes of sweat I've burned that many
> calories. It doesn't feel too hard, relatively speaking
> (though I do Level 15 out of 20 available, with 20 as the
> hardest).
>
> There's also the heart rate monitor that has me at the upper
> celing of my target heart range (which is supposed to be
> ~142-157 for a 35 y.o.) for almost all 40 minutes, which I
> find incredible, too...I definitely look like I'm fit --
> Greco-Roman statue and all -- but it all feels much easier
> than I'd expected (though there is surely a psychological
> component involved, and I've learned fairly well to tune out
> unpleasantries like fatigue, etc.), so I'm wondering whether
> such devices are trustworthy...how are such numbers
> calculated, anyway? On this elliptical, the target heart
> rate seems to come from sensors in the handles....

For the average population probably and there in lies the
rub. I suspect you are way above average. Do it for yourself
not for a machine. Feel good and you will look good. You
asked the wrong question here cause everybody stepped in it
couple months ago with a calorie to heartrate question and
the answer is NO.

[D Stumpus]

"Prisoner at War" <prisoner_at_war@yahoo.com> wrote

> I'm on some elliptical at the gym, have been doing it 40
> minutes three times a week, each session the machine
> read-out claims I've lost ~850-900 calories (range due to
> variable intensity)...how accurate is that?

Probably not very. 850 calories is what a 155# guy would burn
running 8 miles or so. Can you run 8 miles in 40 minutes
(5:00/mile pace)? Do you run at all? That would be national
class talent. That's the kind of output you're talking here...

The heart rate is probably more accurate than the calorie
count. If the heartrate backs off when you slow down, and
increases gradually throughout the session as you get
fatigued, and keep pushing, that's a sign that both your heart
and the monitor are working properly.

> There's also the heart rate monitor that has me at the upper
> celing of my target heart range (which is supposed to be
> ~142-157 for a 35 y.o.) for almost all 40 minutes, which I
> find incredible, too...

Go out and see how far you can run in 40 minutes. Multiply
each mile by the calories per mile given by the following
calculator and see what you get.

Here's a calorie calculator for running:
http://www.stevenscreek.com/goodies/calories.shtml

--
Posted via a free Usenet account from http://www.teranews.com

[Joeu2004]

Errata....

I wrote:
> Back down to 142-157 again, perhaps even lower, for several
> minutes. Then challenge that high level again, perhaps
> slightly lower. Do this repeatedly.

I got rushed. I meant to say: drop down to the __intensity__
where your HR was at 142-157, perhaps even lower. Your HR will
not drop instanteously.

[Robert Gru]

In article
<1170349029.605054.235430@m58g2000cwm.googlegroups.com>,
Prisoner at War <prisoner_at_war@yahoo.com> wrote:
>
>For immediate release from Ye Olde Rambling Question Dep't.:
>
>I'm on some elliptical at the gym, have been doing it 40
>minutes three times a week, each session the machine read-out
>claims I've lost ~850-900 calories (range due to variable
>intensity)...how accurate is that? I find it hard that with
>40 minutes of sweat I've burned that many calories. It
>doesn't feel too hard, relatively speaking (though I do Level
>15 out of 20 available, with 20 as the hardest).

Not very accurate there. But not to worry. It'll be accurate
in a relative sense. If you go and do what it says was 1500
calories, you probably burned off twice as many as if it
said 750. How many that was ... don't really know.

>There's also the heart rate monitor that has me at the upper
>celing of my target heart range (which is supposed to be
>~142-157 for a 35 y.o.) for almost all 40 minutes, which I
>find incredible, too...I definitely look like I'm fit --
>Greco-Roman statue and all -- but it all feels much easier
>than I'd expected (though there is surely a psychological
>component involved, and I've learned fairly well to tune out
>unpleasantries like fatigue, etc.), so I'm wondering whether
>such devices are trustworthy...how are such numbers
>calculated, anyway? On this elliptical, the target heart rate
>seems to come from sensors in the handles....

See my page on heart rate training (though oriented to
runners, the effort levels carry across aerobic activities
fairly well) http://www.radix.net/~bobg/run/hr.html

The target range was computed based on your age, and
some assumptions of where you want to be exercising. But
all estimators have a 10+ beat per minute standard
error. Consequently, my observed maximum heart rate is a
good 15 beats per minute higher than the 220-age
estimator would suggest.

Further, if the targeting from the machine didn't ask about
your resting heart rate, you can, again, be comfortable far
above the level a simpler estimate would say. Again, see my
page for a little calculator and verbal descriptions of
effort levels. Heart rate reserve seems to work much better
for people.

(No, no advertising or the like. Just that I wrote a fair
amount into the page, and don't want to retype it all.)

--
Robert Grumbine http://www.radix.net/~bobg/ Science faqs and
amateur activities notes and links. Sagredo (Galileo Galilei)
"You present these recondite matters with too much evidence
and ease; this great facility makes them less appreciated than
they would be had they been presented in a more abstruse
manner." Two New Sciences

[Prisoner A]

On Feb 1, 3:07 pm, Bill Baka <b...@comcast.net> wrote:
>
>
>
> Mike pretty well has the answer. If you are 35 and only
> working out to the extent of 142-157 then you AREN'T trying
> hard enough. 165 is my average rate sustained for about an
> hour at a time, and geesh, I know people get tired of me
> saying it, but I'm 58 and 165 feels good. Sweaty but good as
> in feeling alive. Don't believe what a generic machine says
> or even the 225 minus age, or whatever you go by. Those are
> just generalizations and probably the middle 50% of the bell
> curve. Mike is 40 and has a max of 205, me, 58 and about
> 185, both outside what the books tell you.

Oh, I've posted in the 160s and 170s, too. But mainly, at ~75
rpm on average on that LifeCycle elliptical, the heart rate
seems to average ~157.

Damn, I wonder how many calories I really do burn up. Is there
a product that can accurately gauge this?

> Greco-Roman statue huh? Snicker. What's your middle name?
> Narcissus?

The wood nymphs call me Adonis.

> Bill Baka

[Prisoner A]

Blast!

Just what are those machines good for, then??

Is there a (portable) product which can accurately gauge my
caloric expenditure?

[Prisoner A]

On Feb 1, 1:04 pm, "D Stumpus"
<dstumpus_N...@mindspring.com> wrote:
>
>
> Probably not very. 850 calories is what a 155# guy would
> burn running 8 miles or so.

What, really!!!!

Then again, I weigh 240 lbs., and an old book I have says one
can generally add 10% for every 15 lbs. over the 150-lb.
standard weight used in caloric expenditure calculations.

Can you run 8 miles in 40 minutes (5:00/mile pace)? Do you
> run at all? That would be national class talent. That's the
> kind of output you're talking here...

I think the ellipitcal machine had me at 3 miles in those
forty minutes....

> The heart rate is probably more accurate than the calorie
> count. If the heartrate backs off when you slow down, and
> increases gradually throughout the session as you get
> fatigued, and keep pushing, that's a sign that both your
> heart and the monitor are working properly.

I'm sure it works, but I was wondering as to how accurate it
could be. Apparently the range for my heart rate as a 35 y.o.
should be 140-160 or something, and I was doing 157, 165,
etc., at various points and it didn't feel too hard....

> Go out and see how far you can run in 40 minutes. Multiply
> each mile by the calories per mile given by the following
> calculator and see what you get.
>
> Here's a calorie calculator for
> running:http://www.stevenscreek.com/goodies/calories.shtml

Will do -- thanks for the ref!

> --
> Posted via a free Usenet account fromhttp://www.teranews.com

[Bill Baka]

Mike R. wrote:
> "Prisoner at War" <prisoner_at_war@yahoo.com> wrote in
> news:1170349029.605054.235430@m58g2000cwm.googlegroups.com:
>
>> For immediate release from Ye Olde Rambling Question
>> Dep't.:
>>
>> I'm on some elliptical at the gym, have been doing it 40
>> minutes three times a week, each session the machine
>> read-out claims I've lost ~850-900 calories (range due to
>> variable intensity)...how accurate is that? I find it hard
>> that with 40 minutes of sweat I've burned that many
>> calories. It doesn't feel too hard, relatively speaking
>> (though I do Level 15 out of 20 available, with 20 as the
>> hardest).
>>
>> There's also the heart rate monitor that has me at the
>> upper celing of my target heart range (which is supposed to
>> be ~142-157 for a 35 y.o.) for almost all 40 minutes, which
>> I find incredible, too...I definitely look like I'm fit --
>> Greco-Roman statue and all -- but it all feels much easier
>> than I'd expected (though there is surely a psychological
>> component involved, and I've learned fairly well to tune
>> out unpleasantries like fatigue, etc.), so I'm wondering
>> whether such devices are trustworthy...how are such numbers
>> calculated, anyway? On this elliptical, the target heart
>> rate seems to come from sensors in the handles....
>
> Don't rely on what your heart rate is supposed to be w/
> regard to your age. Just because you are 35 doesn't mean
> your maximum heart rate is the same as the typical 35 y.o.
> I'm 40 and have at least a 205 bpm HR max. (as indicated in
> the final sprint of a 10K race in Nov.) which is 20 bpm
> higher than what I'm "supposed" to have. Find a means of
> testing your HR max. so that you can determine the
> appropriate target ranges for you.
>
> mike
>
>
Mike pretty well has the answer. If you are 35 and only
working out to the extent of 142-157 then you AREN'T trying
hard enough. 165 is my average rate sustained for about an
hour at a time, and geesh, I know people get tired of me
saying it, but I'm 58 and 165 feels good. Sweaty but good as
in feeling alive. Don't believe what a generic machine says or
even the 225 minus age, or whatever you go by. Those are just
generalizations and probably the middle 50% of the bell curve.
Mike is 40 and has a max of 205, me, 58 and about 185, both
outside what the books tell you. Greco-Roman statue huh?
Snicker. What's your middle name? Narcissus? Bill Baka

[Prisoner A]

On Feb 1, 8:37 pm, Joe Doe <N...@mail.utexas.edu> wrote:
>
>
> But you mentioned you used very high resistance. The work
> output is a function of speed and resistance.

Well, Level 15 out of 20 possible, I said, with 20 being
the hardest.

That's why I'm rather flabbergasted here!

>So it is possible that you burned a significant amount of
>calories because of the high resistance. However you say you
>are relatively heavy. In this case on an elliptical it is
>easy to just shift your weight a bit and let your weight
>drive the pedals so you may be overestimating the work you
>actually did.

Actually, on the few occasions when I cheat by using body
weight, it's on the handles, and hardly evern on the pedals,
just 'cause of the physics/mechanics of the situation....

And I don't think I'm overestimating things...I'm simply going
by the read-out on the machine. If anything, the reason why
I'm asking about read-out accuracy is because I don't want to
overestimate things (based on the machine)!

> I would use a treadmill because it has been used in
> metabolic studies a lot. The equations that the treadmill
> will be using to translate your speed and grade into
> calories burned based on your weight will be much better
> supported by years and years of real data.

Hmm, well, it did take me like 2.75 hours to run 15 miles
once, though I prefer running out-of-doors and have done like
~18-20 miles in one shot (9 times around the Central Park
Reservoir in NYC).

>Here you will actually have to lift your legs (and support
>your own weight) even for walking and the calorie count will
>be more accurate because it is hard to cheat.

Thanks for the tip. I'll look into this (another science
project!).

> Roland

[Joe Doe]

In article
<1170431255.030912.256640@q2g2000cwa.googlegroups.com>,
"Prisoner at War" <prisoner_at_war@yahoo.com> wrote:

> On Feb 1, 8:37 pm, Joe Doe <N...@mail.utexas.edu> wrote:
> >
> >
> > But you mentioned you used very high resistance. The work
> > output is a function of speed and resistance.
>
> Well, Level 15 out of 20 possible, I said, with 20 being the
> hardest.
>

I do not think ellipticals have been out long enough to have
high faith in the equations that machine uses internally to
make the calculations of the work you are doing. These
equations are proprietary so nobody knows if they are accurate
or not. LifeFitness claims they have done extensive metabolic
research to back up their data. I do not know how accurate it
is. I do know that between a Precor machine and a LifeFitness
machine the Precor seems generous in terms of work it says I
am doing at a given exertion levels (12 METS of exertion on
the LifeFitness would be quite hard for me, on the Precor
almost effortless and on a treadmill challenging but doable.
These are differences between the major manufacturers. When
you start talking about no names who knows what equations they
are using. I really trust only the treadmill (almost any
manufacturer). The equations behind a treadmill are known to
everybody and so can be trusted without question. You also
have to realise that the machine has to be in calibration
(calories consumed are a function of grade and speed. If the
machine is wrong in setting speed or grade then the actual
consumption will be wrong too. You should also not be holding
anything - holding could relieve you of doing a lot of work on
the treadmill. (A bicycle ergometer or something else with
lots of research backing it would also be more trustworthy).

>
> Hmm, well, it did take me like 2.75 hours to run 15 miles
> once, though I prefer running out-of-doors and have done
> like ~18-20 miles in one shot (9 times around the Central
> Park Reservoir in NYC).
>

If you can run 15 miles you are ( or were) probably pretty
fit. That is about 5.5 mph which is probably a pretty
respectable pace for a big guy. Being heavy it will be
difficult for you to move fast (unless your are pro football
or basketball player). By setting a high grade on the
treadmill you could burn a lot of calories at a low speed. If
you are overweight & not fit I would not be in a rush to
increase exercise intensity too much because you may already
be at risk for cardio vascular problems. Better to spend a few
months at a comfortable intensity and shed weight if you need
to rather than provoke some cardio event. On all the machines
being heavy you will be burning a lot of calories because
moving the weight is a lot of work.

roland

[Joe Doe]

In article
<1170475137.608160.90410@j27g2000cwj.googlegroups.com>,
"joeu2004" <joeu2004@hotmail.com> wrote:

> On Feb 2, 11:13 am, Joe Doe <N...@mail.utexas.edu> wrote:
> > The equations behind a treadmill are known to everybody
> > and so can be trusted without question.
>
> What are those "well-known" equations? Not intended as a
> provocative comment. I am honestly interested in knowing
> those equations.

For a treadmill & walking(1.9 to 3.7 mph):

VO2=0.1(speed in meters/min)+1.8 (speed)(fractional
grade) + 3.5
ml/kg/min

For running (3.0 to 5.0 mph):

VO2= 0.2 (speed in meters/min) +0.9 (speed) (fractional
grade) + 3.5
mli/kg/min

Once you know volume of Oxygen consumed this can be related to
kcals by the relationship that 1 liter of oxygen used to burn
glycogen = 5.0047 Kcals.

Note everything has to be in metric units km, kg,volume of
oxygen has to be in right units etc.

1 Met= 3.5 ml/kg/min is resting oxygen consumption and can be
subtracted to determine net consumption of the activity.

You can convert VO2 to MET units by dividng by 3.5 or
calculate the conversions directly.

To simplify:

Calories burned = [(V02 consumed by activity)x(weight in kg)
(duration in minutes)]/200

Lastly, I am not an expert on this. I would consult ACSM:
Guidelines for Exercise Testing and Prescription, to cross
check everything I said and find citations about the original
research from which this is derived.

> In any case, no equation can be trusted "without question"
> to be "accurate" for an individual. They might be "accurate"
> for some "typical population". But just how well that
> applies to an individual depends on the sampling used for
> the statistical data, how closely an individual fits the
> characteristics of the sample, and the standard error of the
> average.

I agree that you need to know whether an individual will fit
the population that the regression equations were derived
from. For a treadmill or bicycle ergometer or arm ergometer
published stuff tells you what the equations are and you can
test directly if you want if you are capable of measuring
oxygen consumption. For the other machines who knows?

Roland