When internal frame backpacks were first developed in 1967 by Greg Lowe (who later founded Lowe Alpine and LowePro), they were designed to be more formfitting than external frame packs, bringing the load closer to the wearer’s hips, and making it easier to scramble or go off trail. However, it wasn’t until 1984, that the ventilated backpack frames we know today were first introduced, originally by the German backpack maker Deuter, which first patented the idea.
The first ventilated frame that Deuter introduced had a mesh backing, similar to the one shown above. The mesh creates a ventilation space between the wearer’s back and the backpack, allowing moist air to escape along the sides and top of the mesh. Subsequent tests carried out at the Hohenheim Institute (source Deuter) demonstrated that athletes using the Deuter aircomfort system sweat up to 25% less than non-ventilated backpack systems, enabling better physical performance with less discomfort.
That’s a statistic that I’ve never heard before. I just assumed ventilated (also called trampoline frames) were added to packs because some people find it gross to sweat and stink when they hike, something I just accept as unavoidable.
Thinking it through though, it makes me wonder when the original study was conducted and whether it is reproducible today. Do you really burn less calories if you carry a ventilated versus an unventilated internal frame backpack or is the evaporation process just more efficient?
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I don’t see that it’s about burning less calories; it’s about dissipation of heat….
Why would that lead to better performance? I don’t think I understand the correlation.I added the bit about calories, so forget that for the moment.
Yeah, I don’t see that as a caloric thing. Mistyped? Dissipation of heat can be good and bad. A tight fitting frameless pack will cause your back to sweat. And they are quite warm and act as an insulation layer on your back. Whether this can cause hydration issues or not remains as an open question. I am guessing it would depend on the temps and work you are doing.
The biggest advantage I see to ventilation is in hot dry areas. In the forested areas of the NE USA, I don’t think they help that much. At the normally higher humidity, you sweat with every effort, regardless of the temperature. Down to 40F, my back has been sopping wet from sweating with a Osprey Atmos, a WELL ventilated pack at Baxter Park. Many consider this to be an external frame, actually, but it is an internal framed pack with an airspace. (I use the carry-the-frame-alone-distinction, ie, the pack is only to carry gear, the frame carries the pack.)
If we assume that athletes sweat the same amount with or without a ventilated frame, why would faster drying make their “performance” any better? They’re still going to produce the same amount of sweat (burning the same number of calories) with a given load right? How/why does a drier back improve their performance and under what conditions?
Why does it matter? Deuter tiers their packs, and I assume prices, based on the amount of sweat savings of their different ventilation systems. I’m amazed 1) that they even measure this, and 2) wonder whether other manufacturers price their packs along the same lines.
Performance of athletes has been linked to core temperatures. Athletes that are able to maintain a lower core temperature for a longer time have been doing measureably better in their endurance events. This is why ice vests are popping up more and more at cycling races, marathons, etc; so athletes can drastically lower their core temps before the start of a race.
By allowing sweat to evaporate, and do it’s cooling job, the hiker would therefore be better off. How much performance is gained, as Marco said, that depends on the hiking environment. I know come summer heat, a ventilated frame feels wonderful!
Ice vests – crazy. interesting, but still crazy!
Think about it this way: sweat functions to cool your body by evaporation (it’s a thermodynamics thing), not simply by getting your body wet. If your sweat is allowed to evaporate, you won’t need to sweat as much to regulate your body temperature. However, if your sweat doesn’t evaporate, your body keeps sweating because it is still trying to cool down. This is why you are soaked with sweat on humid days that aren’t really that warm – the air is so full of moisture that it doesn’t readily take on the moisture from your body. If a pack allows for a little more evaporation, your body won’t need to use as much moisture to cool itself, thereby decreasing the amount you need to re-hydrate or the frequency of re-hydration. I think the 25% statistic is supposed to imply you will stay hydrated longer with this pack as opposed to other packs. I think the more interesting question is whether or not that 25% water savings allows you to hike an hour longer without bonking. To me, 25% isn’t notable.
That makes sense – I was just having trouble wrapping my head around it.
I agree though that 25% is probably not a significant benefit, except if you’re hiking in desert!
There is a way too complex cooling glove that football players and the like use. Apparently hands are very efficient heat radiators and you can cool core temperatures quickly with them. – probably explains why it’s hard to sleep with cold feet as I’d expect similar efficiencies in radiation from feet too. So you don’t need an ice vest.
Never tried it, and it’s certainly not where i was taught to cool/heat people in wilderness first aid.
I wonder how long it will take before someone makes backcountry hand coolers in special ultralight performance mesh?
Interesting application for wilderness first aid and heat stress. Certainly a lot less messy than digging an 18 inch deep trench and having someone lie in it to cool off!
I had no idea that football players used these gloves to stay cool. Fascinating.
Less sweat = better hydration = better performance (longer & farther, less cramping, less mineral loss) when your water supply is finite.
Well, the 25% is not significant, really. Compared with the surface area of your entire body, the part coverd by the pack is small. Maybe about 7-10% given a guestimate. So of the approximate 2% improvement over another type of ventilation, It is surely not worth the extra outlay in cash. The slight (2% is slight in my book) improvement *might* be considered after all other avenues of improvement were done. For example, a light wicking cotton, or merino wool shirt will distribute any sweat evenly over your skin and increase evaporative area on the outer surface. Initially it feels a bit warm, but cools you better with any exertion. (I do a bit of running in the mornings and I am a bit surprised that they don’t do that.)
There is also the fact that sweating will excrete metabolic wastes…not just water. This reduces the need to urinate by reducing the amount of water flowing through your kidneys. Working up a sweat is good for a lot of things besides water and hydration.
Muscles really like to be a bit warmer than your body temperature to work best. So warming up is a real thing. but, keeping the muscles from overheating, and your core of course, is usually more of a problem after a few minutes.
Anyway, I think it is mostly break even for the average hiker, with those desert hikers maybe getting more prone to ventilated packs that we are in the NE.
While I can’t cite the original study, nowhere in the article does it state that the 25% applies only to the area that would otherwise be in contact with one’s body. In fact, it states that, “athletes using the Deuter aircomfort system sweat up to 25% less than non-ventilated backpack systems.”
So, reducing the 25% to a mere ~2% via the 7-10% approximation does not appear to be appropriate.
To the point, if I am sweating 25% less, then I am that much more hydrated than I otherwise would be. I know there are other sources of water loss, but if I can get away with drinking ~25% less water to maintain the same level of hydration, that means I can carry less water, too. Less water = lighter pack = MORE of a performance benefit.
As you stated, there are other ways to get rid of metabolic waste…
Haha I love the theorycrafting! Personally I got one because my back would sweat like crazy when I had a non Ventilated pack and it would soak my shirts so thoroughly that by the time I reached a summit, I would be soaked and then get extremely cold even after putting layers on. My new pack has been great in keeping the moisture at manageable levels which is all I really care about, especially in the summer.
25% less sweat from ventilating at an unknown rate from your about 7-10% body surface area??? I don’t buy it. They have to be measuring directly under the pack. The Osprey is slightly better than the Deuter for ventilation and I still drink plenty. It IS nore comfortable in summers 80F days, though.
Sounds like it’s worth contacting Deuter to get a copy of the original study. I’ll look into it. I have a contact there. It certainly is an intriguing issue.
The real truth here is not less sweat enabling better physical performance – vented packs bow the frame out and the whole pack. Thus the centre of gravity is further out and the compensation of this means more energy is used than a framed pack that sits closer to the back hugging you, as you make adjustments and the like on the trail as you are more unbalanced by these packs.
A closer fitting pack with a more natural centre of balance is going to enabling better physical performance. Worth a bit of sweat to get that.
Glen’s newest pack design is carried on one’s head – better postural alignment. You have to go SUL, of course. :-)
I prefer the design on my Gregory Z45. Large lumber pad with no mesh at all. Gives one true ventilation with no material there at all. Works very well. I can slip my hand behind me in the lower back region between the pack and my back. Why even have the “mesh” as I found that meshes tend to be at least half material and thus act pretty much like an extra layer that promotes extra sweating.
By the way have been reading your blog for quite a while. One of my favorite hiking sites. You do an excellent job. Keep up the good work.
Thanks Bob. I’m not big on mesh or shaped pads either but know that many people do.. Would you believe I’ve never tried one of the new Gregorys. Know a lot of people who like them though. Thanks for the comment!
You might not like the Gregory because it weighs almost 4 pounds in a size large. I know your into the ultralights. The pack is extremely comfortable and rugged and fits me perfectly. I tried alot of packs before buying this although not the smaller UL companies because I just couldn’t find many in New Hampshire/Mass./Vermont area.
The prevented water-loss alone would seem beneficial.
My 1st Camptrails had wonderful ventaliation back in 1960’s, then came Lowe’s and sweat.
Lowe’s was designed for climbers to keep the pack close to their back for better balance when climbing or rock hopping and well everyone else just adapted a Climbers pack for a Trail pack and I believe they still do…I then used a Z for a few years and now use a Kestral which is pretty good at airing things out if you don’t wear to many layers and just keep your shirt to a T-Shirt and light jacket. But for real heavy loads like when I am going to hike in for a relaxing week at a specific lake and set up a semi-permanant camp I use my 50th Anniversary Kelty frame pack which has excellent ventalion….So I would suggest that if you want great ventalition no matter what they build and or create an External is still the best..And I notice a lot of folks on the southern trails around here are using Externals and when I asked they said for sweat and comfort reasons…So the trend for trails may be going back to External frames…..
This sounds like marketing nonsense to me. I have a Lowe Expedition from the early 1980’s and a Six Moon Designs Starlite (very similar suspension to the Lowe). Neither one touches my back between the hipbelt and the shoulder straps. Free space has to be better ventilation than mesh.
We had this discussion on a Sierra trek. One of the Scouts was insisting that his external frame pack had better ventilation than an internal frame pack. I asked him to put his hand between my pack and my back and move it up and down. Discussion over.
What I know about packs is that they are hugely a matter of preference. I suppose if its not comfortable and doesn’t have the features you prefer it doesn’t matter how much it ventilates. We could argue about Camelbacks being more aerodynamic than Nalgene bottles if we wanted to.
If you can remember, I would like to know what brand the External Frame pack was that the scout was wearing and whether it was one of the various hybrids that came out with frames that tried to copy Lowe’s which led to the failure of the External market for years…..
The Scout had a Kelty external frame pack. Old school.
Are you sure, for those old packs were rigged just like my 1968 old Camp Trails I used in the and just had a hip belt and shoulder straps and a single wide band of material across the middle of the back of the frame providing no body contact with the bag whatsoever.. Interesting..I wonder if the Scouts had it custom made for them which they tend to do and still do…they currently have a Pack in a Vest type setup that is very hot to wear…
Right. And that wide band of fabric across the middle is exactly what my packs do not have. Nothing touches my back between the hipbelt and the shoulder straps.
Kelty still makes external frame packs.
Screw center of gravity. When you sweat so much that you completely soak through the pack, mesh then becomes a hugely attractive alternative. Personally I don’t like getting weighted down with a sweaty wet pack and trying to wash out the body salts staining it is a pain. Maybe I’m just a “back sweater”
“up to 25%” clearly includes zero percent! If you had access to the original data, you might find that most people showed improvement in the single digits, but one outlier attained 25%. Without seeing the complete study, you don’t know what is statistically significant, or whether the experiment had adequate controls.
Having said that, I have one Osprey and two Deuter packs, all ventilated, and luv ’em!
‘What goes around comes around!’
I developed the A-16 external frame pack in the middle 1950s, Pack ergonomics was a part of the deveopment. Ergonomics is where the truth in backpack design lays.
Kelty was successfull this the original designs and didn’t change the design. As a practicing aerospace designer I knew there would be a next better generatiion and the A-16 external was it. The first padded hip belt with a fustrum, cut form a cone shape. Frame lengthed to improve pack Center of Gravity.
Mesh weave to pass sweat is of little value when there is a layer of fabric under it. Adjustable frame lenght that moved the entre contained pack bag weight. (Patented)
At the end of your blog I see that the ‘External Frame’ gets a high recomendation when the load gets heavy.
Mr. Drollinger, I bought all my basic equipment from A-16 in 1972, The Camptrails Pack of which I wrote and my SEVA 123 which I still have and which cost $16. then and it still works…But by the time I got out to San Deigo and lived there for 30 years..A-16 turned into a “Yuppie Puppie” Palace and all the good gear went away..Could you enlighten us on what happened. The last time I was there I thought I was at JCP’s….
At 87 I still have interests in backpack development. It all comes down to ‘Ergonomics’. One step back from sweat and all the other factors that goes into the design of a pack is ergonomics. They use the word as a sales pitch! If you are going to talk the talk, you should first understand the talk.
The sweat factor is an ergonomic factor!
I trust you are still with us and that you and yours are well.
After about 6 months of fooling around with Alpinelite and Jansport frames (hip arms), I just now ran across the history of your A-16 hip belt Kelty conversion and your company.
Did you ever publish your book on Backpack Ergonomics?
Best regards. .
Has anyone developed a separate piece that can be hung from the top of the backpack straps that provides a ventilated buffer between the backpack and the back?
This could make a lot of money and I would be first in line to buy it.
Meanwhile, I an trying to think if there are other products, (like ventilated car seat pads) that could be converted to this use.
Any ideas or suggestions?
The Deuter Tauren rucksack was made at least as early as the 1930’s. It’s an internal frame with a tensioned and ventilated carry system.