Re: [Phys-l] Food Liar's calorie chart

[Stefan Jeglinski <jeglin@4pi.com>]

> Here, the dominant effect is the rhythmic contraction of various muscles
> which augment the energy converted to heat and to pumping blood to the
> brain.

Based on 2400 nutritional calories per day, we get 50 cal in 30 min 
as a baseline metabolism, which includes baseline rhythmic 
contractions, heat dissipation, and blood pumping. The chart I refer 
to is not sophisticated enough to describe whether the calorie counts 
are in addition to or part of the metabolism, but the numbers to me 
imply in addition to (if the chart had an entry for "no activity" it 
would read 0 cal). My point remains - the difference between putting 
yourself in motion at 4mph and 5mph is not much. Let's say the 
metabolic elevation during exercise doubles to 100, and add that to 
the chart levels:

370 + 100 = 470 (jogging 5 mph)
200 + 100 = 300 (walking 4 mph)

It's a large discrepancy no matter how you cut it.

I've not been able to go through the plethora of reference materials, 
but I have found at least one that claims:

F = 140 cal/mi (jogging, 200lb person) (vs my quote of 148)
F = 133 cal/mi (walking, 200lb person) (vs my quote of 100)

This is much more in line with my original thesis that the numbers in 
the chart I cited are suspicious. I *might* believe that the 
metabolic difference and possible** changes in CM make the difference 
between 140 and 133, but not the other.

Bottom line point - variability in metabolism and nuances of the 
exact form of exercise (the details of F.dx) make small differences 
not worth arguing about. Determining inconsistencies in calorie 
charts handed down like bibles, and explaining them (or being unable 
to), make for a good exercise. I'll leave this part of the discussion 
at that :-)


>  >  it is F.x that determines the amount of energy expended.
>  >  
> Life-forms don't quite follow this relation, which works rather well for
> all too solid masses of other kinds.

Life-forms can't escape the physics that works for solid masses of 
other kinds, I contend. Aside from thermodynamic considerations 
included in the base metabolism, F.x (F.dx more appropriately) 
determines energy expenditure in pumping blood, rhythmic contraction 
of muscles, and moving from point A to point B on a walking/jogging 
surface.

As to treadmills and Bob at PC's humorous attempt to strike fear in 
anorexics everywhere - when running or walking, I claim to be on a 
treadmill called earth. True, I can't really see it moving backwards 
under my feet... or can I? The student can also ponder the energy 
differences, if any, of running/walking on a stationary train, or a 
train that is moving in the same direction, or opposite...

Real treadmills (like in the gym) would have some differing physics 
as to energy dissipation (just ask any walker runner and they'll tell 
you it just ain't quite the same as "real" walking or jogging). 
Treadmills are much better at differentiating "secondary energy 
dissipation" vs running outdoors (wildly swinging limbs, subtle 
terrain variations, wind resistance, psychological factors, etc etc).

**With respect to CM, a few minutes watching Monty Python's silly 
walks skit might convince that you can train yourself to walk or run 
with very little change in vertical CM. For a more convincing 
demonstration, watch someone skilled at moving in Tai Chi or another 
martial art. I'm not buying the change in CM argument (running vs 
walking) at this point. Gotta work the numbers, but I'm not confident 
there's a big difference.


Stefan Jeglinski