swimming for fitness and weight loss

[MJuric]

On Mon, 4 Aug 2003 23:23:42 +0000 (UTC), [email protected] (Jason O'Rourke) wrote:

>Rob Campbell <[email protected]> wrote:
>>things") For a person seventy pounds overweight, it would probably be easier to reduce their diet
>>by 1200 calories than burn it off in a single session. Again, however, if limited the discussion
>>only to the OP's specific case...
>
>If the weight gain took place over 10 years, it is only an extra 70calories a day. 140 for 5. With
>the typical framed woman having a daily need that is at most 2000cals a day, going from 2070 to 870
>isn't going to work well. Realistically I don't think most can reduce by more than 500 under their
>proper daily need. Given time and activities that won't kill the joints (swimming is very good in
>that aspect) one can always build on the exercise side, up to perhaps 2 hours a day.

I agree with your approximation of dropping only 500 calories a day. However I would make
the same recommendation for excercise. If you go out and burn 1200 calories you need to
replace a good portion of those calories (Appr 700) or you will have a similar effect as
cutting your diet by 1200 calories. So since anything we burn over 500 calories in
excercise shoudl be replaced the realistic question becomes which is easier cutting 500
calories from your diet thru caloric control or burning it thru excercise. My contention is
still that it is easier to cut 500 cals than to burn them. It is also better to cut 500
cals as it begins to give you the additional ability of self control and self awareness of
what is going into your mouth. This awareness becomes habit and then a blessing during
those times when excercise is either decreased or interfered with. I've known more than one
injured runner who added on alot of lbs and then had a hell of time taking them off when
they got back to running.

>
>>As a mechanical engineer, it would not surprise me if the error in calculating calorie burn using
>>these rules of thumb is off by as much as 100% in some cases. The simplest estimate would start of
>>by calculating work as load (weight) times the distance it is moved*. This would give the same
>>result for a 100 pound person running two miles as the same person roller blading two miles (flat
>>course). Clearly, those wheels make rollerblading a helluva a lot more efficient, burning fewer
>>calories. This is an extreme
>
>Polar measures by heart rate, which is a very effective approach to measuring work done. But as for
>different running efficiency, you will not see the same variance as your example of running versus
>rolling. The variation would center around how far off the ground each runner lifted his body. The
>work is weight x height. So runners might use 150cal per mile, but 40 on a bicycle.

I've got a Polar 610i. How did you set your's up to measure calories? I was messing (Meaning
not seriously trying to find out) with mine and didn't see anything other than weight that
would effect calories. Right now I'm sure that mine is off (Said I burnt 989cals for a 14+
mile run) and needs to be set in some way, just wondering if you knew how.

~Matt

>
>>legs are flailing all around. So running economy, which a runner can work on, makes a difference.
>>So do biomechanical factors, such as the relative length of the upper and lower legs, which the
>>runner can't change. Efficiency even varies for the same runner by pace. Typically, machines trade
>>efficiency for performance.
>
>As I stated, I ran a given course between 22 and 30 minutes with highly similar results. I don't
>believe efficiency changes all that much, excluding the extreme ends of the scale (100m, or twice
>the training distance). We were built to run and do it well without thinking about it. Quite
>different from swimming.
>
>--
>Jason O'Rourke www.jor.com

 

[Rob Campbell]

"Jason O'Rourke" <[email protected]> wrote in message
news:[email protected]...
> Since the heart rate reflects the amount of O2 being used, which reflects the energy burned, it's
> doesn't seem far fetched to conclude that if you need 3 to 5 extra beats, you are burning at a
> higher rate.
>
> When I run the course in 22 minutes with an average of 178, I burn the same as if I did it at 155
> beats at 30 mins (actually not sure what the HR average was for the slow side). If hot weather
> raised my rate for the same time, then I do believe it would be a higher energy cost. That would
> be an efficiency change. Wouldn't be a huge different though over such a distance.

Heart rate reflects the amount of blood being pumped. It is itself an indirect measure of O2 being
consumed. Even then, any generalization must be based on significant assumptions, as noted in my
previous e-mail.

Disregarding the assumptions implicit in a one-size-fits-all heart-rate-to-energy consumption
conversion, there are a number of stresses that your body can respond to by increasing heart rate,
not just increased effort. On a hot day, more blood is sent toward the skin for increased cooling,
requiring the heart to beat faster. Also, pounds of water can be sweated away, decreasing blood
volume (it's not one to one), requiring the heart to beat faster for the same effort.

> Matt, the polar uses weight, and perhaps age/gender. There's nothing to set. I would treat it as I
> do the tanita BF scales. Not accurate in an absolute sense, but useful in making relative
> comparisons.

Despite all I've written about the likely inaccuracy of these tools and rules of thumb (it's just an
educated opinion until I do serious research, which I don't plan to), I agree that they're useful
for personal use and relative comparisons.

Rob Campbell

 

[MJuric]

On Tue, 5 Aug 2003 17:44:04 +0000 (UTC), [email protected] (Jason O'Rourke) wrote:

>Rob Campbell <[email protected]> wrote:
>>Also consider the other stresses that can affect heart rate. Running in hot weather can easily
>>increase your heart rate 3 to 5 beats per minute. Your heart is doing more work and you feel
>>worse, but the work required to move your weight eight miles, clearly a large component of the
>>total work, doesn't change significantly.
>
>Since the heart rate reflects the amount of O2 being used, which reflects the energy burned, it's
>doesn't seem far fetched to conclude that if you need 3 to 5 extra beats, you are burning at a
>higher rate.

I think Rob's point here is the 3-5 BPM's are not used to burn extra O2. The HR is increased
due to a larger amount of blood being flushed to the skin for heat dissapation. In my
experinace the 3-5 BPM difference is even larger due to heat. So what you would have is an
estimated higher energy expenditure that would be approximately 2-3% off not really a biggy.
This is obviously anecdotal evidence, but here goes. A recent long run on a flat course in
high heat 84 when started 89 at finish and high humidity gave me a Ave HR of around 159. A
similar distance run on a much more challenging course, in lower heat 71 at start 74 finish
with lower humidity gave a 154 Ave hr, despite a slightly quicker pace. This is around five
beats but as I said the difference in course and pace woudl account for a couple more. IMO I
think heat and humidity could make a larger than 5 BPM difference.

>
>When I run the course in 22 minutes with an average of 178, I burn the same as if I did it at 155
>beats at 30 mins (actually not sure what the HR average was for the slow side). If hot weather
>raised my rate for the same time, then I do believe it would be a higher energy cost. That would be
>an efficiency change. Wouldn't be a huge different though over such a distance.
>
>Matt, the polar uses weight, and perhaps age/gender. There's nothing to set. I would treat it as I
>do the tanita BF scales. Not accurate in an absolute sense, but useful in making relative
>comparisons.

Well that kinda sucks. I was hoping there was a test of some sort. Mabey figuring in VO2 or
something like that. If thats the case do you trust the 1200 calories an hour you were
speaking of? Like I stated I did a 14+ miler on Sunday and it came up with 989 calories or
around 70 cals a mile. Damn I'm good, kidding.... You are correct about comparisons though,
it is fairly consistant from excersize to excersize. Maybey I shoudl just lie about my
weight. That would get it up to were it should be.

~Matt

>
>--
>Jason O'Rourke www.jor.com

 

[Mike Edey]

Rob Campbell wrote:

<snip>

> Disregarding the assumptions implicit in a one-size-fits-all heart-rate-to-energy consumption
> conversion, there are a number of stresses that your body can respond to by increasing heart rate,
> not just increased effort. On a hot day, more blood is sent toward the skin for increased cooling,
> requiring the heart to beat faster. Also, pounds of water can be sweated away, decreasing blood
> volume (it's not one to one), requiring the heart to beat faster for the same effort.
>
>
>>Matt, the polar uses weight, and perhaps age/gender. There's nothing to set. I would treat it as I
>>do the tanita BF scales. Not accurate in an absolute sense, but useful in making relative
>>comparisons.
>
>
> Despite all I've written about the likely inaccuracy of these tools and rules of thumb (it's just
> an educated opinion until I do serious research, which I don't plan to), I agree that they're
> useful for personal use and relative comparisons.
>
> Rob Campbell

Do we still take hr's if we drank too much coffee this moring? If we had the flue a week ago? If
we're otherwise overstressed? If it's 4 months later and we're fitter now? If we're experiencing
emotion stress? If we've changed the training run?

The problem isn't that hr's are a 'relative measure' it's that they're a relative measure for
_everything_. The only things I can think of that they're truly usefull for are measuring percieved
effort (sometimes) and as an indicator of general health, or lack there of (increase in resting hr).

As far as measuring caloric expenditure I'm really not sure that there's any 'easy' way to do it at
all. There's no easy way to match the physic's idea of work with the athletes.

--Mike

 

[Dsmoothe]

Hey! If anyone wants a great deal on a Brand New Polar Heart Rate Monitor(well below retail), send
me an e-mail at [email protected]

Thanks

"Rob Campbell" <[email protected]> wrote in message
news:<[email protected]>...
> "Jason O'Rourke" <[email protected]> wrote in message
> news:[email protected]...
> > >As a mechanical engineer, it would not surprise me if the error in calculating calorie burn
> > >using these rules of thumb is off by as much as 100% in some cases. The simplest estimate would
> > >start of by calculating
> work
> > >as load (weight) times the distance it is moved*. This would give the
> same
> > >result for a 100 pound person running two miles as the same person roller blading two miles
> > >(flat course). Clearly, those wheels make rollerblading
> a
> > >helluva a lot more efficient, burning fewer calories. This is an extreme
> >
> > Polar measures by heart rate, which is a very effective approach to measuring work done. But as
> > for different running efficiency, you will not see the same variance as your example of running
> > versus rolling. The variation would center around how far off the ground each runner
> lifted
> > his body. The work is weight x height. So runners might use 150cal per mile, but 40 on a
> > bicycle.
>
> As I said, it's an extreme example to make a point. With regard to the faults of rules of thumb,
> efficiency is more of a factor from person to person. A person's weight is distributed over his or
> her body, including arms and legs that are constantly cycling independent of the forward motion.
> Imagine running eight miles with 2.5 pound weights strapped to each arm and leg.
>
> My caution was about rules of thumb, such as the one you discussed here:
>
> "Jason O'Rourke" <[email protected]> wrote in message
> news:[email protected]...
> > >The rule of thumb for running v. calories is you burn about a 100 per
> mile, no
> > >matter what the pace. Yes, you'd have to adjust this to take into account cardio-efficiency
> > >(probably VO2, as well), but as a rule of thumb, it's
> not a
> > >bad one.
> >
> > Close - that rule of thumb would be true for an average (well to me,
> smallish)
> > sized person. If you're 100lbs, its considerably lower, if you're 200,
> it's
> > higher.
>
> You recognize yourself that it needs to be adjusted by weight, etc. OK, so how do we do that?
> How much?
>
> A heart rate based system is probably better, but is still far from exact. Calories as a function
> of heart rate must have been determined experimentally, with a finite sample of individuals under
> controlled conditions. Those are all assumptions that affect the validity for a general case. The
> assumption that heart rate is a good indicator of calories burned leads to an equation like this:
>
> k*HR*time=calories
>
> where k is a constant of proportionality. According to the rule of thumb you agreed with above,
> distance is also a good indicator of calories burned. So a runner running eight miles at a ten
> minute pace will burn roughly the same calories as if he ran eight miles at a seven minute pace,
> leading to:
>
> k*HR10*80=calories k*HR7*56=calories
>
> k and calories are the same in both equations. We can solve these simultaneous equations to
> find that
>
> HR7= HR10*80/56 = 1.43 HR10.
>
> The difference between my sustained heart rate at these paces is less than this. Perhaps the
> constant of proportionality is dependent on heart rate, increasing moderately with it. That might
> make everything work out. In engineering, that is what is know as a fudge factor. This may be a
> real effect, and the variation with heart rate for a finite set of individuals under tightly
> controlled conditions could be measured, stored in your Polar heart rate monitor, and used to
> calculate calories burned more accurately. But it's another huge assumption.
>
> Also consider the other stresses that can affect heart rate. Running in hot weather can easily
> increase your heart rate 3 to 5 beats per minute. Your heart is doing more work and you feel
> worse, but the work required to move your weight eight miles, clearly a large component of the
> total work, doesn't change significantly.
>
> Engineering, especially mechanical engineering, is not a science. Engineers know this, most lay
> people don't (or haven't even stopped to think about
> it). Engineering laws are not laws of phsyics. We assume linear behavior because it's reasonably
> linear over the intended operating range (perhaps becoming radically nonlinear outside of that
> range). We use strengths of materials that were determined experimentally (by someone else,
> maybe decades ago) under ideal conditions using a finite number of samples. Knowing all this
> and more, an engineer had better have a damned good justification for using a factor of safety
> less than two in any critical, load bearing part. Such as testing of the actual material in
> close-to-final form under conditions that approximate how it will be used. Determining calories
> burned as a function of heart rate or of weight and distance is fraught with similar
> assumptions.
>
> I hope this message didn't come off sounding like a rant. I didn't mean it to.
>
> Rob Campbell