Should we carry our boots in our pack?

[slparker]

Whilst looking at http://bushwalk.com/forum/viewtopic.php?f=15&t=21201&start=30 i looked at some studies completed in regards to footwear weights v energy consumption.

these are the two main findings from the tests that were conducted:

'for each 100 g increase in weight of footwear there is a 0·7-1·0% increase in VO2 (oxygen consumption).

'... it was 6·4 times more expensive (in energy terms) to carry weight on the feet as compared to the back.'

These are single studies, with small cohorts, and generally involved walking on a treadmill (so no elevation gain). The figures are quite surprising though.

In terms of energy expenditure a 700g heavier boot (a 1kg boot v a 300g trail runner) would be consistent with the energy expenditure required to carry an extra 9kg ({6.4 x 1000g x 2} - {6.4 x 300g x 2}) on the back.

What pragmatic use is this information? If you want to save energy expenditure on your walk, at the expense of convenience and cost:

1. Weight should be a major factor in footwear choice, alongside protection and durability.

2. If you need to wear heavy footwear for a particular section of a walk (i.e. a scramble, scree, ice or rock traverse) you are better off carrying your heavy footwear in your pack until it is required. i.e. a boot weighing 1kg would equate to a 12kg (2kg x 6.4)equivalence in energy expenditure worn on the foot (compared to load carriage on the back) but only a 2kg expenditure if actually carried on the back.

If these boots were substituted with a 300 g trail runner for parts of the walk this would equate to an equivalent of 4kg on the back (2x300g x 6.4) + an actual 2 kg (the boots in your pack) = 6kg.
A net saving of 6 kg in equivalent energy expenditure whilst wearing the shoes. And a 600g penalty (the weight of the runners) whilst wearing the boots.

[Orion]

Their metric is "oxygen cost". But there is more to it than just energy expenditure. Weight on one's back has additional costs associated with it, such as muscle fatigue and strains. There's no easy way to count that and balance it against increased energy needs.

I've carried boots in a few circumstances: Ski trips where there were significant stretches of walking on dry ground; and long approaches to ice climbs. In each of those instances I couldn't wait to get those big heavy boots out of my pack and on my feet. I was always jealous of friends who had boots that were reasonable to walk in.

[slparker]

Yes there are pragmatic difficulties with this approach. Boots might be wet, muddy and take up room in the pack and the pack will be heavier by the weight of the boot.

however, in terms of energy expenditure, if these studies are correct, it makes more sense to carry heavy footwear unless it is absolutely required to wear them.

You have to balance weight on the back (or the front with an AARN pack) with actual energy expended.