Exploding Myths: footwear and energy consumption

[Jon Fong / Flat Cat Gear]

If you haven’t done so already, you should subscribe to Gearskeptic on YouTube. Here is a great video where he discusses the common mantra that 1 pound of foot weight is equivalent to 5 pounds in your pack.

 

[jscott]

Wow! Wonderful video!

IF wearing (light)  boots is roughly equivalent to wearing trail runners when out on the trail, in terms of energy expenditure…THEN, what are the advantages of trail runners…?

I might add another wrinkle. If the increased ankle/foot support, and better sole protection, afforded by light boots increases efficiency, as well as comfort…again, what’s the downside of boots?

Some will say, in trail runners, lack of blisters and the freedom of stream wading, where your feet get soaked and you live with it, are the advantages of trail runners.

by the way, I DO notice a difference when I wear sneakers on a day hike, rather than boots. I’m not sure how that translates into energy expenditure versus just a different sensation vis a vis moving my feet.

[Arthur]

These studies are on treadmills or level, smooth trails. Is there a shoe weight penalty when hiking at 2.5 mph going up a 8% grade, a common grade of pack animal trails?   My intuition would make me believe it is significant because one is lifting the shoes, not just swinging them.  But, as we so often discover with research, intuition is seldom truth.

[Jon Fong / Flat Cat Gear]

These studies are on treadmills or level, smooth trails.

This is true, however; 4 to 12 km/hr is a  broad range and I would care to venture that increase speed is probably scaled to slower speed at an incline.  Note 12 Km/hr is 7.5 mph.

 

More importantly, rather than following the herd in thinking the 1 pound feet = 5 lb pack, he digs into the study to point out points out that is not necessarily true.  He didn’t set up the experiment, he just elaborates on the data relative to normal backpacking.  The study was done a long time ago, it would be nice to see an update or elaboration.  I don’t think that anyone but the Army would be willing to invest the time or energy to do this.  My 2 cents.

[Bruce Tolley]

“I don’t think that anyone but the Army would be willing to invest the time or energy to do this.”

I heard a rumor once that it was DARPA funded the research that led to Goretex. The parent company Gore Technologies is a defense contractor.  Curiously, in both WW2 and the Korean War, cold, wet, bad weather caused major losses of effectiveness of infantry in battle.

[Todd T]

Wow! Wonderful video!

Well, mostly.  I’m glad someone took on this rule of thumb and would like to see more on the subject.  One quibble:  He gives a reasonable explanation of “significantly” and notes that the lowest-speed value in that table is not significant, but later assumes the value is correct in explaining why it is not significant (says it’s just too small).  Maybe, but there could be a non-linearity that starts to bite at slow speeds.  My personal experience is that it’s very tiring to hike with someone going a lot slower than I would, especially if going downhill.  Better to simply accept that we don’t know the magnitude of the lowest-speed value.

And I agree with the issue of grade that Arthur noted above.

I wonder if the weight of the hiker matters.  Would the absolute energy numbers he focused on be more important for less muscular hikers (or vice versa)?  What about overweight hikers?

I think it’s also possible the results are dependent on the length of the hiker’s legs.  Movement of the feet is at least partly a rotational thing, and angular momentum varies with the square of the radius.

Sadly, the main reason I probably won’t watch more of his videos is the irritating and distracting hands-waving thing.

[David D]

“THEN, what are the advantages of trail runners…?”

Faster drying time is a pretty significant advantage for runners.  Once my boots are wet and if humidity is high, only my feet can dry my boots and it can take more than a day of dry hiking. Bread bags as VBL seem to speed things up.

[Nick Gatel]

Well, often these kind of things start with Colin Fletcher. In the 1973 (and subsequent  Walker editions) The New Complete Walker, Fletcher wrote:

“Yet the successful 1953 Mount Everest Expedition came to the conclusion that in terms of physical effort one pound on the feet is equivalent to five pounds on the back.”

This probably came from one of the papers written by the physiologist/mountaineer Griffith Pugh, who designed much of the equipment used on the Everest Expedition, with Tenzing Norgay and Edmund Hillary completing the first successful summit. Pugh was an interesting character, here’s a link to Wikipedia.

I suspect Fletcher’s observation has been passed on to succeeding generations as gospel.

All of this begs the question, how does an extra 5 pounds of pack weight affect us? Probably not much.

There is a trail near my house that has an elevation gain of 10,500 feet over 17.5 miles. I have hiked this trail dozens of times over the years. There is a significant difference, for me, wearing leather Danner Mountain Lite boots versus wearing cross country racing flats (59.35 ounces a pair versus 9.8 ounces a pair). I would say the effort with heavy boots is greater than adding 5 lb. to my pack. Of course, all of this is anecdotal.

Hiking where there is elevation gains is different than walking on a treadmill. Exercising on a stair step machine is more tiring than a treadmill.

[jscott]

“My personal experience is that it’s very tiring to hike with someone going a lot slower than I would, especially if going downhill. ”

Like the guy on the video, I think 2.5 mph hiking speed is accurate-ish, for me at least. Of course it varies on different terrain, but mostly becoming still slower as I climb a pass. As for going downhill:

—energy expenditure drops a lot

–it’s precisely then that I appreciate better ankle support and stiffer tread, especially when the trail is rocky and uneven as, well, everywhere in the Sierra.

I’m certainly not wearing leather boots. They’re much lighter than that.

Finally, let me stipulate that my left foot anatomy is…unique. So my requirements are different than most folks’.

[Glen L]

My own experience here in the steep rocky mountainous terrain pretty much mirrors Nick’s experience in his steep terrain. Weight savings on footwear makes a significant difference even at the lower speeds of steep climbing. Sure it would be less so on flatter terrain and ambling along slowly so no equation will suffice in every situation. I don’t care about ankle support but I do care about bottom foot support and protection so I have to make a compromise there.

[Jon Fong / Flat Cat Gear]

Since VO2 is a measure of oxygen consumption, it is a measure of effort.  At faster walking paces the VO2 levels go up.  Hiking up an incline at 2.5 mph will require more oxygen than on a flat surface, so I think that the study is still valid and makes sense.  What we don’t know is the correlation between walking flat and walking on an incline.  So you expect that at a walking speed of 2.5 mph that the VO2 would increase at an 8% grade and 20% grade.  At those speeds and rates, weight should make a difference.

[jscott]

Weight savings on footwear makes a significant difference even at the lower speeds of steep climbing. ”

the video spends several minutes analyzing what the term “significant” means in the Army study; and it turns out, it means “anything more than barely noticeable” in common parlance. I’m going to assume that Glenn and Nick mean something more like “hell yeah I can tell a big difference between wearing trail runners and wearing boots when hiking uphill”.

But Nick compares trail runners to leather boots. I’m not sure what Glenn’s boots are–6 pound behemoths or more like 3 pound per pair (or less) Keen non leather boots. We need to define our terms a bit.

[Jon Fong / Flat Cat Gear]

the video spends several minutes analyzing what the term “significant” means in the Army study; and it turns out, it means “anything more than barely noticeable”

A P value>0.05 typically means that the signal to noise was not high enough. At the lower speeds, the sample size probably needs to be increased to get a better signal. The fact that the sample size was only 16 (probably young men), I am pretty surprised that they got as good if results as they did. Again, rather than focus on the speed think exertion (VO2). Is climbing a steep grade equivalent to walking flat at 7.3 kph? 8.9 kph?  That is the questions.

[Glen L]

I was thinking the same thing about the weight of boots. The full leather Scarpas I have used kind of heavy and I could feel that in knee tendons. There are boots that have less weight so we can’t group them all together. I like the low top shoe type footwear so they weigh somewhat less. My main point is less weight makes it easier to accelerate and that’s about all one does when climbing steep terrain. It’s like in bicycling where the lightest wheels make a difference in climbing and accelerating on the level like in a sprint. It simply adds up in a significant fashion for me, not speaking for everyone. It makes a difference but I believe it’s different than just 1 = 5 for every application. Like Nick said it might be even more for climbing steep terrain. I have no method to acutely measure exactly how much it does for me but my knee tendons say it’s good.

[Dan]

I don’t understand the point of people responding with comments about how they feel/believe that there is a significant difference in wearing boots vs running shoes based on their “personal experience” under some specific conditions.

No offense, but unless your personal experience involves quantitative scientific measurements of your physiological metrics (and the physiology of other randomly chosen subjects), I really don’t care what you believe. If I believed that personal feelings were a valid way to answer a question like this, I would use my own personal feelings, not yours.

The whole point of a scientific study is to actually measure the magnitude of an effect in an unbiased way, and to avoid relying on anecdotal reports and feelings or beliefs. Thanks to the OP for trying to bring some factual information to this issue. Even if the conditions of one particular study may not be perfectly relevant to every scenario, the results are more compelling than vague and qualitative anecdotes.

[Terran Terran]

I know the trail that Nick is talking about. I used to take it up partway and run down it. Steep and rocky with a number of switchbacks. It was fun. Chaco had a water shoe that I liked. Basically neoprene with a thin Vibram sole. I think I would have hurt myself in boots. Boots are best on flat ground. They’re not nimble enough for anything that even hints at being technical. Your feet do more than just hold you up. There’s more to walking than just falling forward. That’s mostly all that boots are good for. Even if they’re lightweight, they bind your ankles so they don’t bend normally.

[David D]

An objective data point regarding boot weight.

My size 13 wide leather Lowa Renegades are 52.7oz a pair.  My old Salomon Quest Prime GTX Boots in size 12.5 are 48.2 oz/pair but a notably tighter fit.  For equal fit, they’re ~ equal weight to the Lowas.

The Salomons are considered “lightweight” for a boot.

Times have changed, leather doesn’t have to be combat boot weight.

[jscott]

“I don’t understand the point of people responding with comments about how they feel/believe that there is a significant difference in wearing boots vs running shoes based on their “personal experience” under some specific conditions.”

hoo boy: where to begin. How’s this: Dan is saying that if the scientists tell you that a specific boot is appropriate for you, and you find these boots to be horrible, give you blisters, make your feet ache: Dan is saying, well, the problem is you. Ignore all that and believe “the factual evidence”

I could go on. Cut to the chase: even scientists recognize that their studies can’t account for INDIVIDUAL circumstances. Scientists’ charts and graphs are based on averages. Each one of us, however, bring our own bodies to the equation. And the equation can’t give us an answer specific enough to dictate a specific shoe or boot that would be best for us.

Given this, despite Dan’s disparagement of your “mere personal experience in the face of objective quantitative analysis” , I encourage folks to buy shoes and boots based on how they feel and work for you in the field. In short: your “mere experience” is in fact where you live.

[Jon Fong / Flat Cat Gear]

hoo boy: where to begin. How’s this: Dan is saying that if the scientists tell you that a specific boot is appropriate for you, and you find these boots to be horrible, give you blisters, make your feet ache: Dan is saying, well, the problem is you. Ignore all that and believe “the factual evidence”

That is not what he is saying or what the video discusses.  The point they are trying to make is that at a normal walking speed (2.5 mph) the effect of the weight of the boot is not statistically significant.  At higher rates of speed (or dare I say incline) that the weight is significant.  Even so, it does not correlate to the 1 lb on your feet to 5 lbs in your pack.

Yes the study is probably biased to young men in the Army and there is a distribution of people out there.  But that is clearly stated on the onset.   Gearskeptic is looking at the raw data and he is correct in questioning the myth of how 1 pound on your feet = 5 lb on your pack.

[Paul Wagner]

There is one more issue involved here.  While weight and effort certainly matter, I have yet to find a trailrunner that works for me when I am carrying a 25lb pack. My feet tend to bruise and hurt at the end of the day if I don’t give them a stiffer sole.  Obviously, YMMV, but my daughter and I just completed 200 miles of the Camino Primitivo de Santiago in Spain, each carrying 15-20 pounds.  I used my lightweight hiking boots. She used trailrunners, and by the end of the first 100 miles she was looking for some kind of inserts to take the pain out of her feet.  Yeah, the shoes were lightweight, but they didn’t protect her from the trail–at least not carrying a pack like that.

[Luke Schmidt]

Interesting how “facts” get repeated endlessly and not questioned.

Personally I felt a difference when I tried a friend’s heavy leather mountain boots after using light trail runners for basically everything. But it might have been more about my leg muscles adjusting. I also feel the difference when I switch from my 6.5 pound rifle to my 7.5 pound rifle. But I’m pretty sure I hike the same with either.

Since moving to Alaska I’ve started using boots more. When it’s 35 degrees and the spongy tundra will soak trail runners instantly, boots make sense. Unfortunately a $200 pair of light boots can wear our almost as fast as trail runners if you go off trail a lot. So I’m eying the heavier leather types and wondering about how the weight and stiffness will feel. I watched a podcast by some Idaho hunters who said they hadn’t found a sub $400 pair of boots that would hold up to a year of their hunting. They went for heavy duty leather boots. For the hunting trips I do I might follow their example. I still like my trail runners for packrafting and light hiking.

[Todd T]

Another complicating factor:  Not every 5 pounds is the same.  Add 5 lb to a 10-lb pack and I won’t even notice.  Add 5 lb to a 30-lb pack and my misery shoots up exponentially.  I’d postulate that the latter 5 pounds would hurt me much worse than a 1-lb heavier boot, while the former one…I don’t know.

[Eugene Hollingsworth]

If we consider weight only –  The difference between my traditional heavy winter boots and my Steger Muklucks is the difference between tired after a 1/2 mile or an all-day hike in the snow. Both boots have similar wide footprint.

[AK Granola]

Wait, so a YouTuber’s fun video is considered a scientific study? I must have missed something. Surely no one would call that science.

[Terran Terran]

A YouTuber did our research for us with citations. Much of his work has been verified and accepted by the community. It wasn’t an end all.  It wasn’t a scientific study. It had much more forethought than simply repeating a phrase. He lays out a good argument. You can accept it or not. I haven’t heard a better one. The 1 to 5 ratio never made any sense. It was generalized misinformation.

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