[pct-l] Backpack Packing strategies...

[CHUCK CHELIN]

Good evening, Glen,



I don’t think you’re confused – there shouldn’t be a proportional increase.
I believe this is because there are two contributors to energy consumption:
The energy for resting metabolism – which is approximately constant – and
the incremental load energy which increases approximately with the load
increase.


One way I look at it is to change the presumption from equal
speed/increasing load to equal load/increasing speed.  With a given load and
at very low speed – say, 0.0001 MPH – the energy cost per MPH will be huge
because of the constant resting metabolism vs. almost no speed.  As the
speed increases the metabolism energy will represent an ever smaller and
smaller percentage of the total energy requirement so the curve will become
non-linear.


I don’t usually work with the oxygen side of energy calculations; I work
with the fuel side in terms of Calories/day, i.e. metabolism, plus
incremental Calories/mile.  http://www.trailjournals.com/entry.cfm?id=166338
The problem is I can only view fuel consumption on a loose, macro basis,
i.e. Calories/day over a long-term, while oxygen consumption can be measured
adequately in the lab in real-time.



Steel-Eye

Hiking the Pct since before it was the PCT – 1965

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

http://www.trailjournals.com/SteelEye09


On Thu, May 12, 2011 at 11:48 AM, Glen Hoshizaki <hoshizaki at ca.rr.com>wrote:

> On page 37 of the paper the investigators defined energy cost as oxygen
> consumption rate per walking speed, all normalized over total mass (body
> mass plus mass carried). So for any given walking speed (at least within a
> certain range) even though oxygen consumption increased with increasing
> load, it did so less than proportionately.
>
> Or am I completely confused?
>
> Glen
>
> -----Original Message-----
> From: pct-l-bounces at backcountry.net [mailto:pct-l-bounces at backcountry.net]
> On Behalf Of CHUCK CHELIN
> Sent: Thursday, May 05, 2011 8:31 PM
> To: Yoshihiro Murakami
>
> Good evening, Yoshihiro,
>
> I have a question about your Interesting Point No. 1:  If more force is
> necessary to move a large mass compared to a small mass; and if energy is
> in
> terms of force applied over a distance, how can it be as you say that
> moving
> a large mass over a distance requires less energy than moving than a small
> mass over that same distance?
>
> Steel-Eye
>
>