Hike conditioning: do lots of short hikes prepare you for long ones?

[Chip Down]

Energy throughput is the cube of the travel rate, so slow down 10% and you'll be using only 3/4 of the energy per minute. That will vastly increase your endurance because you won't be oxygen starved. Your feet and knees won't be pummeled as hard either.

Interesting. I hadn't heard that before.
A dilemma though: just standing with a heavy pack on is fatiguing, so going too slow can be a problem. I suppose a backpacker in poor condition has to be very careful to strike the ideal compromise.

It's interesting to ponder how much more complicated it gets if you factor altitude sickness into the equation. Of course, one would hope that high-altitude hikers are fit, and know their bodies well.

[Webfoot]

Energy throughput is the cube of the travel rate, so slow down 10% and you'll be using only 3/4 of the energy per minute.

This statement is not supported (generally) by sources that I could find.

The energy required to run a given distance is the roughly the same regardless of pace. This is different to walking, where the energy required to walk a given distance generally goes up with pace. This means that at slow speeds, it costs less energy to walk than run, but as you go faster it becomes easier to run.

i.e. rate of energy expenditure is approximately linear with pace up to the point where it is natural to transition to running, though a medium pace of ~2.5 MPH is most efficient.

Other references that I found not as directly quotable on this point but which I believe are relevant:

https://core.ac.uk/download/pdf/82357089.pdf

https://www.physiology.org/doi/full/10. ... 01177.2001

[raven]

Pure physics: kinetic energy varies as mass times velocity squared for a given distance. you get there faster with higher speed, so cubed. I've checked this with an engineer friend in a car with various speed head winds and car speeds.

With running the gate changes making the flats a matter of comparing apples and oranges. Try climbing a hill below your aerobic stress level and your pulse in repeated trials on the same trail, at different rates of climb as measured by the total time to cover the same section of trail, tells the tale. Don't forget to consider a base level speed.

Eyeballing the graph shown, going from 22 to 16 minute walking pace increases the calorie throughput by 10 calories per mile, then to 10 minute mile by another 20+, 1.1 cubed is 1.33; close fit to what I said.

[aiwetir]

I say forget the math and go hike.

There is a documented phenomenon that walking slow repeatedly stops your momentum making you stop-start each step essentially. Walking a bit faster conserves your momentum a bit making faster walking more energy efficient up to a point obviously. Going uphill/downhill changes everything in regards to energy expenditure.

AFAIK cubed comes in with wind resistance there's not much wind resistance at walking and running speeds but as a cyclist it's a major factor with us. I've always heard it increasing as the square, not cube though.

One interesting tidbit. For decades we had calculations on energy expenditure while cycling, weight vs speed on flat windless terrain (computed from lab testing also) and when they put power meters on bikes, found that the actual expenditure was somewhere between 1/2 to 1/3 of prior estimates. So that cool 6000 calorie ride you just did got knocked down to about 2400 calories. I think putting someone on a treadmill in a lab is a great way to estimate what you get running/walking but it's completely different in the real world.

[Aimless]

I've always figured that my most efficient pace was the fastest pace I can maintain for an hour without feeling the need to stop to rest or catch my breath. That 'fastest' pace can vary within any one hour, as the trail varies in slope or throws a bunch of roots and rocks in my path. At the moment, my typical 'best' pace seems to be right about 2 mph uphill when the trail is gaining about 500 ft. of elevation per mile. On such a trail I tend to hike consistently for several hours with only brief breaks for water. I find my overall downhill speed is only marginally different, because I've expended a lot of energy by the time I'm headed downhill again, and my rest breaks get longer to compensate.

This has nothing to do with science or math. It is what feels right, based on long experience. Faster or slower just misses my sweet spot.

[Webfoot]

Pure physics: kinetic energy varies as mass times velocity squared for a given distance. you get there faster with higher speed, so cubed. I've checked this with an engineer friend in a car with various speed head winds and car speeds.

Air drag is not a predominant energy cost in walking. Talk about apples and oranges!

Eyeballing the graph shown, going from 22 to 16 minute walking pace increases the calorie throughput by 10 calories per mile, then to 10 minute mile by another 20+, 1.1 cubed is 1.33; close fit to what I said.

You're cherry-picking your data; from the same graph if you go from 2 MPH to 3 MPH you actually gain efficiency so your energy output would be less than 50% more. There's no point in looking at 10 minute miles walking as other gaits are better. My point stands; the third degree rule you postulated is not generally true.

I say forget the math and go hike.

But math is fun.

I've always heard it increasing as the square, not cube though.

Drag force is a second order, but since work is force over distance you have to multiply again by velocity, yielding a third order function for power.

when they put power meters on bikes, found that the actual expenditure was somewhere between 1/2 to 1/3 of prior estimates.

I'd like to read that. Do you have a link?

[aiwetir]

when they put power meters on bikes, found that the actual expenditure was somewhere between 1/2 to 1/3 of prior estimates.

I'd like to read that. Do you have a link?

I could look for one, but I also know this from experience. Even just the other day I went for a ride without power or heart rate and all the modern automagic computer calorie calculators I use told me it was 700 calories. I know if I wore a hrm it would likely have told me around 400 and a power meter would probably be around 250-300. A quick online search for a calculator also told me 726.


EDIT: Here's an article with one example showing a 28% difference (as opposed to 200-300%) with a citation at the bottom, however as I said. Nearly every ride I did before getting a power meter had 2-3x the calories I burned after I got a power meter

[arlohike]

I agree that math is fun and I love a good chart, but the car comparison doesn't seem relevant. Besides the dramatic difference in wind drag between walking and driving speeds, a car and a human body have different mechanical issues that come into play. That is, they are both more or less efficient at different rates of effort, but for different reasons. And then humans and other animals have different ways to move, some more efficient than others in different scenarios ... I assume that's what the walking vs. running chart is getting at. Our bodies even have two different energy conversion systems, aerobic and anaerobic ... although that makes an interesting comparison with hybrid gas/electric cars.

[raven]

I should have said, "other things equal", which in a complex system such as the human body, is never the case. At question is the work done. Clearly holds for lifting a weight to a mountain top, or to fighting a head wind. The automobile experiment provided me with a datapoint fitting the power rule to reality. Bodies mostly supply anecdotes and personalized knowledge.

A friend of mine, then recently a competitive crew racer, who in the about 7 minutes of a race would become fully exhausted, commented when discussing this very subject, that while a race would exhaust him, he could "go all day at 75%". Agai,n doing a calculation would be complex, but he spent years learning how to have all his muscles run out of steam at the same time, and had a lot of experience working out at different effort levels.

As I said in answering the original question about conditioning by a writer who likes to go all out: slow down; learn to travel longer; adjust to the new interval.