Feb 7, 2009 at 4:48 pm #1233876
Robert BleanBPL Member
@bleanLocale: San Jose -- too far from Sierras
Assuming that the only difference between two hikes is distance, total ascent, and total descent, is there a way to compare how strenuous they are. Assuming all else is the same (load, weather, temperature, altitude, both on trail, etc), which is the more strenuous hike.
The answer is presumably obvious if one is bigger in all figures. But if one is longer with less total ascent the answer is less obvious.
There was an old guidebook rule of thumb that calculated time to hike a trail at 2 mph + 1/2 hr per 1000' ascent. For the sake of this question, it does not matter whether that time is accurate — just whether a trail with a longer calculated time will be more strenuous or not.
Would that metric work well? Do you have a better way to predict which will be the more strenuous?
If there is a good way to do that, then the next obvious question is how to factor in altitude.
— MVFeb 7, 2009 at 5:11 pm #1476112
Tom KirchnerBPL Member
@ouzelLocale: Pacific Northwest/Sierra
You put your finger on one additional variable, i.e., altitude. Another factor might be how the elevation is gained: steady gradient; steep gain all at once; repeated ups and downs with an upward trend. Another factor might be
trail surface: rocky, slick, sandy, roots and stones, overgrown, etc. Exposure needs to be considered, too. Then there's the individual's mental frame of mind. How do you deal with all of the above mentioned variables. Do you relish a steep in-your-face grind? Roots or brush freak you out? How about exposure? I think you get the picture.
My $.02Feb 7, 2009 at 5:15 pm #1476113
Piper S.BPL Member
@sbhikesLocale: Santa Barbara (Name: Diane)
I lead Sierra Club hikes and in our local area we just assign ratings like strenuous or moderately strenuous. It's so completely arbitrary as to be useless. Call a hike moderate and people will show up who have never exercised and want to follow their doctor's orders to get some moderate exercise!
Some of the other groups have better rating systems that will rate a hike based on steepness, how fast people intend to go, how difficult the terrain is and other things.
Sometimes being 95 degrees and no shade is enough to make a flat 5 mile hike more strenuous than a 10 mile hike on a comfortable day in the shade.
Anyway, my point is it is really hard to create a system that can provide an objective measurement.Feb 7, 2009 at 9:44 pm #1476155
When I was trip planner / advisor for an adventure group I used the following methods (I also found much of the method useful to determine which direction to hike on loop hikes):
Load the trail into a topo application and observe the trail's profile. Calculate the elevation gained and lost for the hike (most do this automatically).
For a typical day hike this might be 500-1,000 feet of elevation change once you count all the uphills and downhills for even relatively easy terrain.
For loop trails and determining direction, look for steep uphills or downhills and determine your groups abilities as well as where it will fall in timing. Some people with knee problems have major issues doing down steep slopes, others find the uphills killer (usually in mixed groups that have people packing heavier weights). Also, sometimes it's far wiser to handle a large climb early on on a multi-day and end with a relatively easy route after that.
The easiest way of telling the steepness of a hike is it's grade, again the software can usually do this for you. (Grade = elevation/distance x 100) To give a point of reference on grade: A typical road is generally less than 6%. Between 6% and 8% it's usually signed in the US, if the hill is of any significant length, to warn trucks. 8% to about 11% is extremely rare on anything except mountain switch backs.
In addition, calculate things such as soil type (sandy and loose stuff makes it harder) as well as elevation, weather and other terrain important issues. Anything above 8,000 feet in elevation is going to be significantly harder on a lowlander even if it's a completely flat trail.
As an example, lets take a hike to Crystal lake in Rocky Mountain National Park. It's a typical out and back but for the sake of calculation let's just figure it going one way. (all numbers from Delorme Topo USA and may be rounded a bit)
Start Elevation: 8,600 ft
End Elevation: 10,300 ft
Distance: 7.3 miles (38,544 feet)
Climb Elevation: 3,572 ft
Desc Elevation: 616 ft
Average Grade as 11%
From looking at the above, you can see that it doesn't have much of any downs hill, but is instead an uphill trudge most of the way. With those conditions I'd suggest only fit hikers attempt the trail, especially due to the higher elevation so it would receive a rating of moderate/strenuous.
Now on the other hand, if we go to the trail to the south the Beaver Mountain Trail (a loop trail) has the following stats:
Start/End Elevation: 8,900 ft
Distance: 6.8 Miles
Climb/Desc Elevation: 1,347 ft
Max Elevation: 9,247 ft
Min Elevation: 8,434 ft
Average Grade: 9%
Overall, this trail has far less climb / desc elevation change. At 1,347 ft and average grade of 9% that'll put it in the range of yes there are some up and down hills, but they are less steep and it's overall lower altitude combine to make it a milder trip than Crystal Lake. It also has about as much uphill as downhill as compared to a solid uphill slog. However, with a peak elevation of over 9,000 ft elevation acclimation for a few days before starting is recommended to help reduce the affects of altitude.
For those wanting an example with a little less elevation, take the Paddy Creek Wilderness Trail in Missouri. It is again a loop so obviously it will have the same elevation for start and finish.
Start/End Elevation: 1,255 ft
Distance: 14.5 Miles
Climb/Desc Elevation: 2,300 ft
Max Elevation: 1,290 ft
Min Elevation: 889 ft
Average Grade: 6%
So here we've got a longer train, so the climb / desc elevations will be larger numbers. But, take a glance at the 6% grade, so you know that overall, the hills are mild. But, take a close look at your min and max elevation, they are only 400ft different. Basically, to get that much climb and desc without much change in overall elevation you are currently looking at a very "lumpy" trail, so there will be almost no flat spots but instead it's up/down/up the whole trail. On the plus side, the low altitude and relatively mild terrain makes that something I'd put on the easy side of moderate for a typical hiker. If it wasn't for the constant ups and downs it'd easily be rated an "easy".Feb 8, 2009 at 7:25 am #1476210
Greg MihalikBPL Member
nm – (some day I will remember to read from the top before posting.)Feb 8, 2009 at 1:33 pm #1476265
@ryanLocale: Northern Rockies
I love this kind of math.
I've been working on a Universal Formula for Trekking Difficulty for fifteen years.
Gotta love Excel.
Recently, I've approached it from a different perspective: that of calibration.
1. Weigh yourself, and your food, at the trailhead.
2. Weigh yourself, and your food remaining, at the end of the hike.
Of course you can get more complex than this with BMI calculations, caloric density, vitamin deficiencies, etc. etc. but then we're in the realm where the exercise ceases to be fun.
Using the differences in those figures, you can make a guess as to how many calories you burned from start to finish.
Let's say your answer came to be … 25,000.
Now we have to normalize that somehow into a measure we all understand, like miles traveled.
So if this was a 50 mile hike, then we divide 25,000 by 100 miles, and we get a difficulty rating of 250 Cal/mile.
The trek has to be pretty long to get good results, otherwise you need to back out water weight in your body to get accurate results.
But do this for a few of your 7+ day treks and you'll start to get a feel for how difficult a route actually is.
More specifically, you get a feel for how much energy your body required to complete that route in the style you chose, which means the difficulty of a trek depends on a lot more factors than simply distance, elevation gain, altitude, etc.
Pace (how fast you hike), ground cover (e.g., snow), tempo (how many miles per day you hike), etc. can have remarkable impacts on how much energy you expend on a hike.Feb 8, 2009 at 3:31 pm #1476308
"So if this was a 50 mile hike, then we divide 25,000 by 100 miles, and we get a difficulty rating of 250 Cal/mile."
Wouldn't you be dividing by 50 miles in your example to get cal/mile?
Also, while Cal/mile would be good at comparing trails after the fact. For a group or for projecting expectations I'm not sure how that would play out.
However, if we were to modify the calculations for "work" in the term of physics (work=force overcome x distance)" calculations to take the following into consideration we might have something more interesting:
(Weight of hiker + base weight + average weight of consumables) x distance traveled forward = work for forward movement
That above would only be accurate for a flat plane, so we have to figure a way of determining the work used for the grade as well
(Weight of hiker + base weight + average weight of consumables) x elevation gained = work for elevation of the trail
If we add them together we get:
w = Weight of hiker
b = base weight
c = average weight of consumables
f = distance forward
e = elevation climbed
((w+b+c) x f)+((w+b+c) x e) = work needed to hike the trail.
I believe with a bit of modification we could get a decay rate included for a more realistic weight of consumables for trips with resupplies, or even a decay rate for those without resupply.Feb 8, 2009 at 3:47 pm #1476312
As an addendum to the above, I'm not sure that it qualifies for the "work" formula. It'd be true if we were pushing said hiker up the trail, but I'm not sure what formula would be appropriate.
It would spit out a number useful in comparing one hike to another but from what I read it wouldn't apply to converting the joules into calories and saying that x many calories of energy are needed to hike that trail.
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