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Hiking Speed and Trail Steepness

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Postby Ze » Thu Feb 25, 2010 1:45 am

graham wrote:Interesting symmetry to the Iron Mtn graph.

The right side (uphill) of the graph make perfect sense to me (steeper = slower), but I’m surprised that you don’t have more scatter on the left side (downhill).

I know Iron Mtn has some steep and rugged downhill sections (maybe class 2) that require some slow and careful foot work. But there are also clean downhill sections that you can really motor down and would expect to be at least as fast as on level terrain; hence a lot more variability to the left side of the graph (downhill). Am I missing something?

Do you have a sore knee, ankle, etc. that slows you down on the descents?


Yeah I would think there would be more variance...however I don't think I would be going as fast as on level terrain (unless it was a race). I think there is a comfort level (again related to impact or eccentric contractions). When you move fast on a steep downhill, you will have large impact forces and also large joint excursions in the opposite direction of the muscles contraction, and this creates lots of muscle damage (in a good way) = soreness. Perhaps only a certain threshold of this is allowed unless I "overrode" my subconscious.

I don't think it had much to do with the looseness of the terrain, as you'll notice even in the trail run the same trend is there (Although it seems slightly faster downhill than up).

The downhill wasn't controlled in these examples, but sure is interesting...
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Postby nhluhr » Thu Feb 25, 2010 3:19 am

I was thinking about this exact topic the other day while following my wife down a very steep 'hiking trail'. Going up, she kept remarking that we'd make much better time on the return. I was dubious. I am talking about a grade of near 100%. Sure enough, the return trip was no faster through the steep portions where there were no switchbacks.

I feel the limiting factor is largely aerobic when going up and largely that of balance/technical-skill on the way down, which may account for the clearly correllated difference in shape of the negative and positive grade halves on your plot.

Speaking of grades, I think the chart would be more visually relevant (to readers) if the units were in grade percentages, so they can relate it to things they see in real life (which are almost always in percentages). Although, this wouldn't change the shape of the curve at all...
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Postby Ze » Thu Feb 25, 2010 5:06 am

nhluhr wrote:Speaking of grades, I think the chart would be more visually relevant (to readers) if the units were in grade percentages, so they can relate it to things they see in real life (which are almost always in percentages). Although, this wouldn't change the shape of the curve at all...


I agree, I actually intended to but forgot to multiply by 100 before making the graphs, and I was too lazy to redo them :)
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Postby The Chief » Thu Feb 25, 2010 5:15 am

What happens when ya throw on a 75lb pack and start your "hike" at 10k and your destination is roughly at 12.5k in three miles?

What would be the speed equation then at the same grade as the OP?
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Postby RickF » Thu Feb 25, 2010 8:03 am

The Chief wrote:What happens when ya throw on a 75lb pack and start your "hike" at 10k and your destination is roughly at 12.5k in three miles?

What would be the speed equation then at the same grade as the OP?


Chief makes a very good point. And in my opinion there are more variables than just the degree of incline and pack weight that affect rate of travel. Some of the other key variables include the type or ruggedness of the terrain, altitude, the general condition the traveler(s).

In the past I've given in to over-analyzing estimated travel time for some longer trips and then found that its usually controlled by the speed of the slowest member of the group.

I have a simpified travel rate tool in an Excel spreadsheet. First I break down a trip into segments based on six generalized travel modes ranging from the easiest to the most difficult:
Class 1 trail
Class 1 trail w/ full pack
Class 2 x-c scramble
Class 2 x-c scramble w/ full pack
Class 3 climbing
Class 5 climbing

Then for each travel mode I apply a horizontal travel rate and a vertical travel rate. My horizontal rates range from 3 mph for easy trail walking carrying only a light day pack to o.5 mph for the hardest off-trail technical terrain. I use two sets of vertical rates, one for ascending and one for descending. Ascending rate components vary from 2,000 ft per hour to 250 ft. per hour while descending rates vary from 3,000 ft. per hour to 375 ft. per hour.

(I tried tp insert an example of one of my Excel worksheets but it didn't display right)

I've tested this theory a few times and found it to be pretty accurate. For solo trips a lot depends on how I feel the day of the outing. When I go with a partner, or a party of friends, the group only travels as fast as the slowest individual.
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Postby Ze » Thu Feb 25, 2010 2:59 pm

I agree. I'm not stating it's some all-encompassing thing...more like a baseline speed / grade relationship before other factors are considered like the ones you mentioned. It would be interesting to compare this curve with another one 1) while carrying a heavy backpack 2) over various tough terrains 3) at altitude
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Postby nhluhr » Thu Feb 25, 2010 4:44 pm

FortMental wrote:
nhluhr wrote:I was thinking about this exact topic the other day while following my wife down a very steep 'hiking trail'. Going up, she kept remarking that we'd make much better time on the return. I was dubious. I am talking about a grade of near 100%.


At a grade of %100, your return trip should have been much, much faster. Way faster. If you were a ball.
Well, if I was a ball, I never would have gotten up the trail. Does that create a divide-by-zero error?
Ze wrote:I agree. I'm not stating it's some all-encompassing thing...
True! Nothing chartable can account for ALL permutations. I don't see why everybody has such a case of the ass about somebody who is graphing actual data and attempting to explain it. Perhaps some of the conclusions you drew from the data were questionable but I found the plots very interesting.
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