Hiking Speed and Trail Steepness

[Zé]

For anyone interested in a little GPS analysis, I did a little study on the relationship between trail steepness and hiking speed.

[KathyW]

Interesting.

I'm not sure if this is relevant, but here's my unscientific study on the length of legs, the steepness of hills, and speed: If you have short stubby legs, there's less of a variance in speed as the grade of the slope increases than if you have long legs. Short legs are slow on the flats but they don't do too bad on the steeps. Long legs are fast on the flats and they don't do too bad on the steeps, but it's definately a more significant decline in speed between flats and steeps for people with long legs.

[Zé]

I think that's relevant. At low grades, your 'max speed' is going to be determined on other factors like leg length & mechanics as opposed to max energy.

There are studies on this. I know they find people prefer to walk around 3 mph for economy. As in, if you are going to walk a mile, walking it at 3 mph will take the least amount of energy total (although the rate would be higher than at 2mph) And I'm sure this could vary by leg length.

[Florian]

I find my uphill and downhill speeds are usually about the same. Going down is less of a cardio load of course but i'm being more careful where i step and also my feet tend to get tender so i slow down.

-Florian

[zippetydude]

Interesting thought, I like it. I especially like the way you superimposed the two curves to get a greater overall picture of what is happening. Smart.

I have a similar question about oxygen consumption.

I notice that going up Whitney, when I'm pushing hard I actually experience tunnel vision due to oxygen deprivation. On the way down, even when pushing equally hard, my respiration is not challenged.

Wow, that's very different. There must be a huge difference in oxygen consumption to make that kind of difference, but I don't have any clear way to quantify it.

Got any thoughts?

z

[bluerail]

...my head hurts. and I think my toupe's gonna catch on fire.

[Zé]

Interesting thought, I like it. I especially like the way you superimposed the two curves to get a greater overall picture of what is happening. Smart.

I have a similar question about oxygen consumption.

I notice that going up Whitney, when I'm pushing hard I actually experience tunnel vision due to oxygen deprivation. On the way down, even when pushing equally hard, my respiration is not challenged.

Wow, that's very different. There must be a huge difference in oxygen consumption to make that kind of difference, but I don't have any clear way to quantify it.

Got any thoughts?

z

How do you think / know that you were pushing just as hard downhill? It is generally a lot less work going downhill.

Best way to quantify and verify would be to wear a heartrate monitor, and see how those numbers compare uphill and downhill.

[zippetydude]

By "equally hard" I meant approximately the same speed, not same exertion level. I was wearing a heart monitor - average hr on the way up (while running) was about 158, on the way down, about 109. You suppose heart rate correlates accurately with oxygen consumption? I don't have a formula to account for cardiac drift, so the downhill rate, even at the same pace, may be a bit inflated.

z

[Zé]

yes you can assume a good linear relationship (although heartrate can vary based on other factors)

as workload increases, O2 consumption will increase.

for O2 consumption to increase, heart must pump more oxygenated blood.

with stroke volume (strength of one heart contraction) about constant, it's the frequency of beats that gets more O2.

so makes sense that its a good amount lower while going downhill, and at 109 you were probably able to absorb enough oxygen even at altitude

[bluerail]

( although heartrate can vary based on other factors)....are you making jabs at old people ?