[pct-l] Backpack Packing strategies...

[CHUCK CHELIN]

Good morning, ,

I would like to congratulate the researchers at University of Michigan,
Department of Mechanical Engineering and Biomedical Engineering, for
creating a strong case in support of the long-elusive perpetual motion
machine.  The claim is all of the energy used to accelerate a walker’s mass
upward during a step is fully compensated by retrieving that same energy
when the mass is subsequently accelerated downward, thus making the event
totally energy-neutral and independent of the magnitude of the mass.  If
that were the case, the weight of one’s body and one’s load would be
irrelevant to energy consumption.

This same basic logic can be applied to a discussion of the effect of
wearing heavy boots compared to light shoes:  If energy is necessary to lift
and accelerate a foot forward one step-length, all that energy – supposedly
– is available to pull forward and lift and accelerate the opposite foot
once the first foot has returned to the ground; again, a perpetual motion
cycle that is independent of mass.  If that were the case, the weight of
footwear would be irrelevant to energy consumption.

While I’m uncomfortable with the usefulness of assumptions that walking is
on a flat surface and has zero mass-related parasitic energy loss, I totally
reject the applicability of this perpetual motion theory to actual hiking in
the mountains.  When walking uphill – you’ve probably noticed that there’s
quite a bit of that on the PCT -- energy is expended to raise one’s body
mass, i.e. increasing one’s potential energy, sometimes thousands of
vertical feet without relent.  If the perpetual motion theory were applied,
all of that increase in potential energy would subsequently have to be
recaptured on a compensating downhill portion of the trail.  Regrettably,
such is most defiantly not the case.  Potential energy is indeed absorbed
going downhill, but rather than being available to assist in ascending the
next uphill, it is rejected by the body as waste heat.

I’m often amazed to see the extent to which heavy-weight hikers will go to
justify their preference, but for me the most persuasive counter-argument
can be found by actually walking uphill with a pack.  Based upon years of
experience carrying loads varying from minimal to massive I can say this:  The
effect of carrying a twenty-pound pack uphill can definitely be felt;
carrying a forty-pound pack is very tiring; and trudging up the trail with
an eighty-pound pack is somewhere between exhausting and painful.  How can
that be?  Isn’t walking is supposed to be energy-neutral?

I own many, many pounds of gear – much of which would make my trip more
comfortable if I were to carry it – but I leave all but 8-10 pounds at home
because weight matters.  I am very happy hiking in the “unbearable
lightness” category.

Steel-Eye

Hiking the Pct since before it was the PCT – 1965

http://www.trailjournals.com/steel-eye

http://www.trailjournals.com/SteelEye09


On Sat, May 14, 2011 at 4:33 AM, Ernie Castillo <erniec01 at hotmail.com>wrote:

>
> Excellent information.
> So now those "heavy truckers" can come out of the closet.
> More credence to "hike your own hike" philosophy.
> There are multiple ways with which one can remove fur from a feline.
>
> Ernie Castillo
> PCT Class of 1980 and a former heavy trucker
>
>
>
> > Date: Sat, 14 May 2011 16:04:50 +0900
> > From: completewalker at gmail.com
> > To: hoshizaki at ca.rr.com
> > CC: pct-l at backcountry.net
> > Subject: Re: [pct-l] Backpack Packing strategies...
> >
> > Dear Glen
> >
> > The oxygen consumption is widely used as an energy cost among
> > Ergonomics professionals, because it is valid and reliable index.
> >
> > This article clearly indicated that the energy cost significantly
> > decreased during walking with load than without load, and the load on
> > the upper back condition was more energy saving than lower back
> > condition.
> >
> > The contradictory result, that the with load condition was energy
> > saving, may be perplexed you. But, these result may be well
> > interpreted by the recent dynamic walking model ( inverted pendulum
> > analogy). That is, if the pendulum movement might be facilitated by
> > the pack weight, energy expenditure will decrease.
>
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