Subject: Calories per minute (long)
From: mannj@southern.co.nz (Jay Mann)
Date: Jan 16 1996
Newsgroups: misc.fitness.misc
Summary: Calorie cost of walking,jogging, cycling compared

There has been considerable discussion in this newsgroup about the
energy costs of different kinds of exercise.  Here's some more data.

I recently found an old reprint in my files,  a paper by Henry A Bent,
entitled "Caloric Costs of Mass Transport" (J Chem Education 55:526-527
(1978).  This quaintly titled article actually deals with calory
expenditure in human walking and running.

The author states that the cost of covering one mile is about the same
whether you run fast or slow (10 mph or 8 mph) = 120 kcal/mile for a 70 kg
person.  For a 140 kg person (or a 70 kg person carrying a 70 kg load),
the calory use is double.  (One kcal is the same as 1 Calorie.)

"In summary, the caloric cost of transporting a mass horizontally, by
running or jobbing is (not coincidentally...) of the same order of
magnitude as the caloric cost of transporting the same mass the same
distance vertically".  In other words, we jiggle up and down as we move.
"Running and walking are a series of forward falls followed by
recoveries."

Using a simplistic stiff-leg model, the up-and-down movement accounts
for all the experimentally measured costs of locomotion. But real
runners bend their knees, saving about 1/3 of the bobbing; real runners
have to accelerate and decelerate arms and legs, though, which accounts
for the rest of the energy used.  Old people, backpackers, and tired
walkers take small steps, thus reducing the up-and-down costs.

Bicycles, by eliminating the bobbing, take about 4 kcal/min at 8 mph =>
30 kcal/mile.  So an hour of cycling takes 240 kcal = 2 hot dogs, 2 soft
rolls, or 2 large bananas.  It takes 0.05 horsepower to maintain 8 mph.
Move to 22 mph touring or 25 mph in racing position, and you need to
provide 0.5 hp = 24 kcal/min.  On treadmills, trained cyclists can only
maintain 0.2 hp over four hours, but they can do 0.3-0.4 hp on the open
road when air-cooled.  Champion 24-hr cyclists maintain 22 mph speeds,
15 kcal/min => 20,000 kcal deficit that takes several days of heavy eating
to satisfy.

The maximum human sweating rate is 2 liters/hour = 20 kcal/min of
cooling.  To remove the 2400 kcal/day normal diet purely by evporation
would take 4 liters (20 glasses) of water a day.
 
Interesting figures:
Simply living consumes 1.67 kcal/min = 2400 kcal/day.  Presumably this
includes normally activities including those below:
 
Sleeping        1 kcal/min
Standing        2
Walking 3 mph   4   =>  80 kcal/mile
Running 8 mph  16   => 120 kcal/mile
"    " 10 mph  20      120 kcal/mile
 
One slice of bread = 80 kcal = about 1 mile walked
One lb of fat tissue metabolised = 3500 kcal =~ 44 miles walked
 
[sorry about the mixture of lb and kg above, it comes from the original
article.]
 
Jay Mann      <mannj@southern.co.nz>
Christchurch, NZ

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.physics
Subject: Re: A simple Energy problem
Date: 8 Jan 1999 08:18:21 GMT

In <F580Lz.IHq@presby.edu> jtbell@presby.edu (Jon Bell) writes:

> Thomas Stewart <tstew@montana.campuscw.net> wrote:
>
>> A 130 pound woman steps up on the aerobic step a distance of 2 1/2
>> inches 40 times/minute for 40 minutes. How many calories did she burn?


   In general, that's not a "simple energy problem" because it's a
biological as well as a physics problem.  All you can easily calculate
is how many calories of work she does.  But muscles are horribly
inefficient, and the amount of food calories she actually must burn to
do this work may be 5 or even 10 times larger.

   Work in metric units, always.  Work is force times distance, and the
force here in mks metric units (Newtons) is the woman's weight (mg),
which is her mass (in kg) times g (9.81 m/sec^2).   The distance is 2.5
inches x 1600 steps = 40 feet.  Convert this to meters, and multiply by
the force in Newtons to get work, which wnow be n Joules.  Divide by
4.184 to get calories, or by 4184 to get classic "food Calories"
(capital C) which are actually kilocalories.  Than multiply THAT by
your 5 to 10 fudge factor to see how many chocolate bars it's going to
burn off.  Or divide by 3000 to see how many pounds of fat it's
equivalent to.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: misc.fitness.weights,misc.fitness.misc,sci.med,sci.med.nutrition
Subject: Re: VO2 max percentage
Date: 11 May 1999 04:17:55 GMT

In <37373C55.5A7F3761@stud.tu-muenchen.de> alex
<alexander.kralj@stud.tu-muenchen.de> writes:

>recently i read a bunch of interesting articles about heart rate and
>training but i became slightly confused when there was written about
>'training at 100%vo2 max OR ABOVE'. how is it possible to train ABOVE
>one's 100% vo2 max since 100% is the *maximum* !?


   It's only the maximum aerobic limit.   Thus, you can exceed it, but
not for long.  What happens is that the extra output is anaerobic, and
soon drives you to the wall (partly from acidosis, but there are many
factors).  It's what distance runners and cross country skiers do in
that final few hundred yards, the idea being to reach your absolute
aerobic AND anaerobic limits just as you hit the end of the race. (In
Scandinavian cross country skiing, when you pass the last Lapp, you
know you're getting near the Finnish line).


>secondly vo2 max can be compared to heart rate. i guess 100%vo2 max then
>would be comparable to maximum heart rate (e.g. 200 bpm).


   No.  Even the most fantastic endurance athelete may hit VO2 max
somewhat before hitting max heart rate.  Couch potatoes and those
without endurance training seem to hit VO2 max at lower heart rates
than well-trained people, however, probably because they hit a limit in
ability to extract O2 from blood, and increasing cardiac output after
that doesn't help them any.  Part of training is in being able to
increase stroke volume more with increasing heart rate, and some of the
rest of the training effect is in becoming able to come to extract more
than 25% of the oxygen in the blood as it passes the capillaries (which
is all you do at rest).  Well-trained people can go down to around 50%
extraction.


> what then would be the vo2
>max percentage at resting heart rate (e.g. 40 bpm)?

   You can't tell, since this differs by training.  A cross country ski
champ at best might run a heart rate of 40 at rest, and have rest be
only 5% to 7% of VO2 max (so his metabolic scope is 15 to 20 times
resting VO2).  That does not mean that the man can increase his HR by
15 or 20 times.  Rather, O2 extraction doubles, stroke volume goes up
by factor of 2 also, and HR increases by 15/4 to 20/4 = 4 to 5 times
(to 160-200).  For a thirty year-old, this can be well under absolute
max of 190-200.


>what then would be the heart
>rate at 50% vo max [200bpm-40bpm/ 2?] ?


   For a very well trained young adult athelete, perhaps midway between
resting HR and calculate max HR will put you in the ballpark (of the
guy above, 40 + 75 = 115).  For couch potatoes, there is no telling.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med,misc.fitness.weights,misc.fitness.misc
Subject: Re: VO2 max percentage
Date: 13 May 1999 07:52:21 GMT

In <373A7970.ECEFA06@wireco.com> Daniel Carmody <carmodydw@wireco.com>
writes:

>Hmmm... a myth dispelled... maybe... I would be inclined to believe more
>wholeheartedly if you could tell me the biological source of the
>soreness?


   Probably the same cause as when somebody hits you in the muscle with
a baseball bat.  Damage is done.  Inflammation is invoked.  Nerves are
stimulated.  Generally if you exercise hard enough to have soreness in
a muscle the next day, your CPK levels will have risen a bit,
indicating a least a small amount of muscle damage and leaking muscle
cells.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med,misc.fitness.weights,misc.fitness.misc
Subject: Re: VO2 max percentage
Date: 13 May 1999 08:43:08 GMT

In <3739E051.B4E3A147@stud.tu-muenchen.de> alex
<alexander.kralj@stud.tu-muenchen.de> writes:

>thx for your reply,
>that would make sense. i read that glycogen is the main energy source for
>areobic activity above 60% vo2 max. there is no opportunity for me to
>measure vo2 max so i came to ask about values comparable to vo2 max (like
>heart rate). thus i wondered what would be the heart rate when muscles
>get depleted of glycogen. but then i think that type of exercise would
>also play a decisive role- if one's gheart rate ascents to fuel only one
>muscle-group then there you would probably have a higher vo2 max than in
>each muscle if you fuel all them all together at the same heart rate. do
>i understand this right?
>	alex


    I can't make any general statements here-- too much depends on how
well trained the athelete is and how long the duration of the aerobic
stress is.  For example, you're going to run out of glycogen long
before you finish a triathelon, and yet the best atheletes certainly do
the last half of this at above 60% of their VO2 max.

    If you want to know moment by moment what fuel an athelete is
burning (glucose or fat) there is really only one way to find out:
calorimetry.  Lots of studies have been done, and their basic message
is:  people differ a lot.  Generally most glycogen is gone between 3-4
hours, and after that you run on about half fat and half carbohydrate
from gluconeogenisis.

   BTW, I realize on re-reading that the figure I gave you for where
half max VO2 should be, in terms of heart rate, in a trained athelete,
is low.  You get near your max increase in stroke volume by the time
your heart rate has increased halfway from resting to max, so by the
time he gets to that rate a trained athelete will have gone to far more
than half his VO2 max.  In fact, he'll probably be at more like 2/3rds
of it.  To get to 50% VO2 max a well trained person needs a HR of only
about 25% to 30% of the difference between resting and max HR.  Sorry
for the mixup.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med,misc.fitness.weights,misc.fitness.misc
Subject: Re: VO2 max percentage
Date: 13 May 1999 20:52:00 GMT

In <7hf844$o1$1@murdoch.acc.Virginia.EDU> ejk4e@node6.unix.Virginia.EDU
(Edward James Kilsdonk) writes:

>Oh lactic acid will get your attention, do not mistake that.
>But it does so during and immediately after anaerobic
>exercise.  And it clears up fairly quickly during recovery.
>DOMS is a very different critter.
>
>Although, I have had a squat workout that left me with sore
>legs a couple of hours after leaving the gym, and where the
>soreness did not go away for four or five days.  But it did not
>feel like lactic acid, i.e. less burning and more aching.
>
>Ted K.
>
>ps, let us know if you want to know what lactic acid feels like
>and Whitney and I can probably give you some playful anaerobic
>threshhold workouts <grin>



"Feel the BURN, majesty.."

      Boopsie's earlier reincarnation as trainer to Cleopatra


================================================

  There's a good article in this month's _Discovery_ magazine about a
guy who won a deep knee bend contest in prison, and wound up in the ER
two days later with red urine, going into renal failure.  I've seen
this syndrome myself several times-- the one I remember best being in a
guy cought in a rip tide who tried to swim in instead of parallel to
the shore, and strugged way beyond his normal endurance.  It's quite
possible to trash even trained muscles if you excercise them hard
enough.  The fibers break down like tenderized meat and the myoglobin
plugs your renal tubules.

   Whatever the mechanisms are, they involve oxidation as at least a
secondary problem, since a number of experiments have shown that both
delayed onset muscle soreness and the CPK rises which mark such muscle
damage (especially in excentric exercise, as you note), can be
influenced for the better with large doses of vitamin E taken every day
for some weeks previously.  Which is why there's hardly an endurance
athelete over 30 who doesn't take the stuff.

From: Steve Harris <sbharris@ix.netcom.com>
Newsgroups: misc.consumers,sci.med
Subject: Re: How much time do you have left?
Date: 8 Apr 2005 13:42:58 -0700
Message-ID: <1112992978.635144.273390@l41g2000cwc.googlegroups.com>

The life expectancy calculator is rigged anyway. Who says (for example)
that you'll get an extra 4 years of life from exercise? Maybe you don't
live longer, but it just seems like longer, ala the old joke. I don't
even know of any epidemiological studies that show *that* big an effect
on the general population.

In any case, even if you find one, it still doesn't prove exercise
isn't just a marker for relative health and wealth, like driving a BMW.
People who exercise are healthier indeed, but which is cause and which
is effect? Does jogging prevent emphysema, or does emphyema prevent
jogging? Exercise makes you feel better, but never confuse a feeling of
righteousess with slower aging (he says on the day of the Pope's
funeral). Show me the randomized trial, if you think that exercise (or
prayer or whatever) makes you live longer.

Meanwhile, I'm going to assume that exercise is like Premarin and
vitamin E and being married and going to church and blah blah. They all
look great epidemiologically and the chemicals had a nice story for why
theyt should be good for you. But when studied prospectively to take
out the false statistical associations that arise from looking at
disparate groups, vitamin E and premarin flunked completely. So might
exercise and churchgoing. Of course I can't be sure of that, until the
trial is done.

Heretically Yrs (from the couch on Sunday),

SBH