SummitPost.org

I was reminded by questions in another thread that I should write this up. In some ways its obvious but I think good to understand a little more.


http://hikingscience.blogspot.com/2010/08/why-moving-little-too-fast-can-cost-you.html

So did I get this correct:

Due to altitude and pressure's effect on the ability to get oxygen into bloodstream, the aerobic threshold drops to a lower level, thus leading anaerobic burn at a lower pace?

Exactly.

This sounds like a good explanation of the "dash and crash" climbing style. I certainly enjoyed reading it but since I've never been it that great of shape I wouldn't mind reading something about your fourth category.

Hmmm this goes against years of practicing "The best way to warm up is to blow up".

Brad Marshall wrote:This sounds like a good explanation of the "dash and crash" climbing style. I certainly enjoyed reading it but since I've never been it that great of shape I wouldn't mind reading something about your fourth category.

lol, well there's a similar effect between fat and glycogen use. the slower you go the more fat you use so you spare glycogen and you'll be able to go for longer. unless you're at 3% bodyfat!!!

Ze wrote:lol, well there's a similar effect between fat and glycogen use. the slower you go the more fat you use so you spare glycogen and you'll be able to go for longer. unless you're at 3% bodyfat!!!

So the new "light and slow" climbing style my friend (RIP) and I started developing over the past couple of years appears to be on the right track. I'm certainly not in a hurry to get to the top and don't mind losing a few pounds along the way.

PS. It's not that I'm not in shape. As my wife always says "round's a shape".

What?? Where exactly does the snickers come into the picture?

Brad Marshall wrote:So the new "light and slow" climbing style my friend (RIP) and I started developing over the past couple of years appears to be on the right track. I'm certainly not in a hurry to get to the top and don't mind losing a few pounds along the way.

PS. It's not that I'm not in shape. As my wife always says "round's a shape".

If you were fixed by time and not distance, then higher intensity would burn more calories (and likely more fat, but not always). But yeah since you already know how much work you are going to do, slower will burn more fat. But it's probably not that clear, fat metabolism is some complicated crap with a bunch of hormonal interactions that makes my brain explode when trying to read about!

castricone7 wrote:What?? Where exactly does the snickers come into the picture?

lol actually, after a very long day of hiking recently I bought chocolate milk and a large snickers bar. honestly it had great recovery effects! (not sure if you meant that 'snickers' though)

FortMental wrote:

Dubzion wrote:So did I get this correct:

Due to altitude and pressure's effect on the ability to get oxygen into bloodstream, the aerobic threshold drops to a lower level, thus leading anaerobic burn at a lower pace?

That's only a first order approximation.

Could you clarify that just a bit? English is not my native language, and I'm afraid I didn't understand your reply.

I have found that the older you get, the less you have to worry about going too fast
Also, your endurance for longer distances increases by maintaining a slow but steady pace.
Here is an interesting article about hiking every day
http://article.wn.com/view/2010/08/31/G ... of_cancer/

Ze's reference wrote: Well you should know that altitude has lower pressure and it's harder to get oxygen into the bloodstream and to the muscles. This means that if you are moving at a certain speed / workload, you are getting less of your energy from aerobic glycolysis, and more from anaerobic glycolysis!

I'm not doubting that there is an altitude effect, but it needs to be explained better. The above statement would be true only if the oxygen uptake rate was already at or near maximum, and couldn't be increased. It fails to account for the ability to increase the oxygen uptake rate by breathing faster and thus returning to the original aerobic/anaerobic ratio. Of course, breathing faster slightly increases the workload and oxygen needs, making it impossible to maintain the same hypothetical speed and workload as altitude increases.

Ze's reference wrote:When you are hiking the last few miles up to the summit of Mt Whitney, you are already going slow as you can because of the low pressure

In addition to the missing word, this certainly isn't true. Although I'm sure others have been to the top of Whitney more than I have, I've never seen anybody move "as slow as they can" as they approach the summit.

foweyman wrote:

Ze's reference wrote: Well you should know that altitude has lower pressure and it's harder to get oxygen into the bloodstream and to the muscles. This means that if you are moving at a certain speed / workload, you are getting less of your energy from aerobic glycolysis, and more from anaerobic glycolysis!

I'm not doubting that there is an altitude effect, but it needs to be explained better. The above statement would be true only if the oxygen uptake rate was already at or near maximum, and couldn't be increased. It fails to account for the ability to increase the oxygen uptake rate by breathing faster and thus returning to the original aerobic/anaerobic ratio. Of course, breathing faster slightly increases the workload and oxygen needs, making it impossible to maintain the same hypothetical speed and workload as altitude increases.

Ze's reference wrote:When you are hiking the last few miles up to the summit of Mt Whitney, you are already going slow as you can because of the low pressure

In addition to the missing word, this certainly isn't true. Although I'm sure others have been to the top of Whitney more than I have, I've never seen anybody move "as slow as they can" as they approach the summit.

You are right in theory, but in practice that's not the case...I guess I am speaking more of hiking without significant acclimation. People increase their ventilation/breathing but not enough to account for the decrease in pressure, probably because of hyperventilatory side effects they aren't used to. But after some length of acclimating, the adaptation would be better. That would be good to clarify.

As for the second quote, I'm exaggerating obviously. (And I'm too lazy too proofread, so thanks ). But it actually goes with your point; even though there is lower pressure ~14,000 ft, there's still plenty of oxygen pressure to do a lot of work, but people move slower when not acclimated and are avoided too much anaerobic metabolism.