Skyline times?

General Palm Springs area.

Re: Skyline times?

Postby Wildhorse » Mon Jun 11, 2018 8:07 am

I usually move more slowly going downhill. It seems to put more stress on my body, and I am usually tired from a hike by the time I go downhill.

I imagine that differences in times going up and down are at least partly affected by accumulated injuries as we age and by whatever traumas our bodies may be guarding against consciously and unconsciously.

My favorite hikes are slow and off trail. My speed on these hikes varies with the physical and navigational difficulty and with danger of falling.

And some days I am just slower, or faster, than others depending on how I am feeling physically and emotionally, and on the weather. I have learned much about myself on mountains.
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Re: Skyline times?

Postby Ed » Mon Jun 11, 2018 8:32 am

I was once speedy downhill, but am now there with Cynthia and WildHorse. After doing the downhill on even a moderate hike, I feel very beaten up. I dread the last few hours coming down the Vivian Creek Trail more than I do the last few hours going up Skyline. I am sure some of it is due to my wobbly knee, the rest to age.

Hiking uphill, I start off doing Naismith's Rule speed or better, then begin slowing down after a few hours. To match Naismith's Rule for the entire hike, a moderate one, I would have to hike 3 mph downhill. I am way below that.
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Re: Skyline times?

Postby zippetydude » Tue Jun 12, 2018 2:42 am

I should qualify my 60% statement. It is only valid where there is a normal, walkable (is there such a word?) trail. For example, if I started at Ramon and went up to the stone cairn, and turned around there and went back down then the rule would hold. If I started at the museum, then the super steep, rather technical descent on rocks with gravel and loose sand would probably be more on the 1:1 ratio mentioned above. On fairly smooth trails, though, I find the huge drop in effort makes a big difference. BTW I totally agree about the Vivian experience for those last couple of miles!

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Re: Skyline times?

Postby Wildhorse » Tue Jun 12, 2018 6:31 am

Hi Z, One reason I am slower going down steep trails is that I am often quite fast going up steep trails. But I imagine you are also fast going up. Did the downhill speed come naturally to you or was it a skill you developed?

I have guessed that my own slower speed downhill may involve muscle imbalances that I don't fully understand. Core work seems to improve my pace. From what I have read, it seems that asymmetries and traumas from injuries or repetitive stresses are constantly causing issues, such as the ones that slow me down. Of course, so many other factors affect performance. Weather, food, body systems, emotions, etc.
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Re: Skyline times?

Postby Ed » Thu Jun 14, 2018 9:43 am

zippetydude wrote:Downhill time is almost always 60% of the uphill time.


Zip,

Check Tobler's Hiking Function.

https://en.wikipedia.org/wiki/Tobler%27s_hiking_function

As I read the table, downhill time is about 2/3 of uphill time for grades of 10-15 degrees. So you are a speedy downhiller!
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Re: Skyline times?

Postby zippetydude » Fri Jun 15, 2018 8:05 pm

...or a lazy uphiller! BTW, I found the formula and the graph interesting, but I'm thinking that to represent reality it should probably be more of a bell shaped curve, or somewhat more parabolic at least. Still, it's all for fun and he's given it a great deal more thought and effort that I have, so I totally appreciate his efforts.

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Re: Skyline times?

Postby Ed » Sat Jun 16, 2018 10:07 am

It does seem like the function for speed should be curved at the maximum. But the reciprocal function for pace is not very sharply curved at the minimum. Some of the references are interesting, at least for those of us who are quant nut-cases, it seems there is quite a literature on this subject. There are various extensions of Naismith's Rule, Tobler's Function, etc. which have been empirically tested. The original data for Tobler's Function seems to have come from Swiss soldiers. Strange that they had no adjustment for altitude.

By the way, I calculated the ratio of downhill time/uphill time for 10 and 15 degrees, and it was 0.7. So you are looking even speedier on the downhill run.
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Re: Skyline times?

Postby pdforeme » Sun Jun 17, 2018 8:07 pm

My down time is generally 80% of my uphill time. My math is simple, that is, i live/hike mostly in NW hikes that are 4 miles up a canyon to a lake, then back downhill. So i'm just comparing the total up to the total down. I suspect some of the near parity comes from pausing at times on the descent to give the right of way to the uphill hikers.
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