Body Mass and Pack Weight

[photohiker]

As for AARN style of packs (or Double packs as they are called in the research papers), the military have done a lot of research into them and as it has been suggested, they are the most energy efficient way of load carriage this is because the most efficient way of load carriage is to keep the load on your center of gravity and at least on flat terrain the double pack does this very well but according to the literature the double packs are not with out problems, (I have not used an AARN pack or even seen one, this information is from scientific research articles) in the reports that I have read about double packs some subjects report over heating, restricted breathing and in rugged terrain, view obstruction, however one study reported that "there was an percentage increase in march time when using the double pack, whatever the load" Thus 6% (light load); 14% (medium load) 28% (heavy load) (Charteris 2000).Tony

Beware. An aarn pack is not a 'double pack'

A classical double pack is just that. You put one pack on your back, and another on your front. There are system packs that allow you to add a pack to the front by attaching it to the main harness. I often see this type of loading on photography hikes I have been on, and it takes a very strong and fit individual to keep it up for long if there is any weight in the forward pack. There is high pressure on the shoulders, and the person wearing the packs has his breathing restricted and the airflow around their body eliminated. They overheat, and they cannot breathe adequately. Additionally, they cannot see their feet or the trail they are walking on. Might be ok in the military for short haul trips.

This is not in any way similar to an aarn pack, where the emphasis is to remove weight from the shoulders, place it on the hips, and to carry balancing pockets out the front and away from the body so that airflow is not restricted. Breathing is restricted less than with a standard pack as the upper body is not restricted by the harness. (watch someone's shoulders without a pack and breathing hard to see that shoulders are involved in breathing) The wearer still has full view of their feet and the trail.

[Tony]

Hi under10kg,

(I have not used an AARN pack or even seen one, this information is from scientific research articles) in the reports that I have read about double packs some subjects report over heating, restricted breathing and in rugged terrain, view obstruction, however one study reported that "there was an percentage increase in march time when using the double pack, whatever the load

In my experince of using several Aarn pack models in Australia and New Zealand, the front balance pockets of Aarn packs do not overheat the body due to the internal frame system design. This holds the balance pockets away from the body and allows full air flow. These can be customised for woman with large busts.

When scrampling, one can undo an attachment to the balance pockets and move them out of the way for hard scrambling. This allows a full view of ones feet etc. Personally, I like the even front/back balance weight distribution when scrambling as you feel so much more balanced.

You need try an aarn pack to see how it makes load carring much more easy. They are a bit more of a fiddle to put on.

Thanks for your views, I found this in one of your earlier posts

( I am being totally honest about this even though Aarn is my brother so I could be accused of bias)

I am just reporting what I have read so far about double packs and I still have reservations about over heating with an Aarn pack, I have also read that this could be used to advantage in cold weather.

Tony

[Tony]

Hi photohike,

Beware. An aarn pack is not a 'double pack'

A classical double pack is just that. You put one pack on your back, and another on your front. There are system packs that allow you to add a pack to the front by attaching it to the main harness. I often see this type of loading on photography hikes I have been on, and it takes a very strong and fit individual to keep it up for long if there is any weight in the forward pack. There is high pressure on the shoulders, and the person wearing the packs has his breathing restricted and the airflow around their body eliminated. They overheat, and they cannot breathe adequately. Additionally, they cannot see their feet or the trail they are walking on. Might be ok in the military for short haul trips.

This is not in any way similar to an aarn pack, where the emphasis is to remove weight from the shoulders, place it on the hips, and to carry balancing pockets out the front and away from the body so that airflow is not restricted. Breathing is restricted less than with a standard pack as the upper body is not restricted by the harness. (watch someone's shoulders without a pack and breathing hard to see that shoulders are involved in breathing) The wearer still has full view of their feet and the trail.

Unless you can prove otherwise I will have to disagree with you on this one.

A double pack is a just that a pack on the pack and a pack on the front whether it is supported on the shoulders, the hips of both and to me an Aarn pack comes under the double pack configuration. According to (S Legg Influence of backpack straps on pulmonary function) traditional backpacks can restrict breathing even with relatively light loads.

Tony

[ninjapuppet]

I have recently been doing some research into backpacks or as the scientific circles call it "Load Carriage" with the idea of putting my findings together to start a similar discussion on bushwalk.com.
Tony

thats great tony. I dont know if you've come across this, but the university of SA school of physiotherapy ran several studies of backpacks about 10 years ago. I used to help them collect data on school kids over a period of 5 years, and many studies were conducted from that data set. its mainly based on school kids but you might be able to find some really good background info on backpacks from some of those studies, such as how the spine reacts to differnet loads, and what vertabrea level is optimal for the backpack's center of gravity to be located at. just try to google unisa backpack studies

heres one such study
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC111061/

[photohiker]

Hi photohike,

Unless you can prove otherwise I will have to disagree with you on this one.

A double pack is a just that a pack on the pack and a pack on the front whether it is supported on the shoulders, the hips of both and to me an Aarn pack comes under the double pack configuration. According to (S Legg Influence of backpack straps on pulmonary function) traditional backpacks can restrict breathing even with relatively light loads.

Tony

Well, I can offer the initial proof that I have personal experience of all three types of pack personally: Normal, double, and Aarn. You say you have not even seen an aarn pack, so I would expect to have a small benefit of doubt, but up to you. I can assure you that a double pack and an aarn pack are very different beasts as already described.

Have you any links to the double pack research you speak of?

[Nuts]

Seems like an odd thread, its turning into another discussion about backpacks (and brands) rather than 'loads', starting to focus on one in particular (much, i'm sure, to the delight of U10 )

Seems odd that a chiropractic association would 'recommend' ANY load to be carried regardless of pack design, let alone one overengineered and obviously so to take a Heavier load....

The intital post has led in a few directions though as some have suggested there are no real 'rules'. To me the only rule has got to be 'less is best' Surely!... but then it gets back to the sticking points these ideas usually find in the 'lightweight' threads and no doubt will meet with the same tired list of caveats

Just to add perhaps a useful comment that maybe a short mat could be used? The short exped (or neo) mats do save a bit of weight (and take up less room... ie a smaller pack?) The empty backpack could be used under the feet anything not breakable or squashable left inside?

Last edited by Nuts on Tue 09 Mar, 2010 7:52 pm, edited 1 time in total.

[north-north-west]

I agree with scavenger in thinking it is basically a mental or psychological thing. women get told their whole life that they cannot carry this, that they need help when lifting that.

I've been getting the 'not a woman's job' bull all my life. As a kid I played with the boys more than anything because girls' games were, to me, stupid and dull. So I ran and climbed and threw and fought and whatever with the boys. Much more fun. And whenever someone started with the 'proper little ladies don't do that' garbage I just ignored them. Still do.
So I don't think twice about hefting around 15 - 20kg loads at work, even when some of the blokes look for an easier way to do it. And a lot of that is knowing how to lift, rather than pure body strength, anyway.

IMNSHO, a proper load is what you're comfortable carrying. End of story.

[Tony]

Hi ninjapuppet,

thats great tony. I dont know if you've come across this, but the university of SA school of physiotherapy ran several studies of backpacks about 10 years ago. I used to help them collect data on school kids over a period of 5 years, and many studies were conducted from that data set. its mainly based on school kids but you might be able to find some really good background info on backpacks from some of those studies, such as how the spine reacts to differnet loads, and what vertabrea level is optimal for the backpack's center of gravity to be located at. just try to google unisa backpack studies

heres one such study
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC111061/

Thanks for the link I had not come across that paper before but I have read some similar ones, I will print it off and read it tonight. There seems to be a lot of very good research into young people carrying school bags these days.

Tony

[Tony]

Hi photohiker,

Hi photohiker,

Unless you can prove otherwise I will have to disagree with you on this one.

A double pack is a just that a pack on the pack and a pack on the front whether it is supported on the shoulders, the hips of both and to me an Aarn pack comes under the double pack configuration. According to (S Legg Influence of backpack straps on pulmonary function) traditional backpacks can restrict breathing even with relatively light loads.

Tony

Well, I can offer the initial proof that I have personal experience of all three types of pack personally: Normal, double, and Aarn. You say you have not even seen an aarn pack, so I would expect to have a small benefit of doubt, but up to you.

I will state that I am not knocking Aarn packs, I think they are a very good design that works on the design principle of keep weight distributed around your natural center of gravity, I was only reporting what I had read in some scientific reviewed papers which anecdotal evidence struggles to stack up against.

I have looked seriously at the Aarn packs for some years now but early on decided that with the type of walking that I do I would have overheating problems and from what I have read recently I have not changed my mind, as I practice the lightweight philosophy I do not need an Aarn pack.

I can assure you that a double pack and an aarn pack are very different beasts as already described.

From pictures and descriptions they look the same to me.

Have you any links to the double pack research you speak of?

Here is one for starters http://eprints.ru.ac.za/669/

I have many papers that mention double packs but unfortunately they are not available to the general net user, (I work at a university and have access to some but not all, some are available only if you pay)

Tony

[photohiker]

Hi photohiker,

I can assure you that a double pack and an aarn pack are very different beasts as already described.

From pictures and descriptions they look the same to me.

Have you any links to the double pack research you speak of?

Here is one for starters http://eprints.ru.ac.za/669/

I have many papers that mention double packs but unfortunately they are not available to the general net user, (I work at a university and have access to some but not all, some are available only if you pay)

Tony

Thanks for the link Tony.

I'm happy to continue to discuss this, but I also agree that this thread is becoming polluted by one brand of pack.

The on topic information from the linked study is that we are all wimps - they tested the double packs with up to 61kg on board!

Michael

[under10kg]

I send Aarn a copy of this thread as it would be good for some input from the designer of these packs. Seeing a picture of these packs and actually trying out one are 2 different things. Hopefully he will respond in time. Just for the record I do not use an Aarn pack when doing short walks, but use a frame less pack and light gear.

[Taurë-rana]

I send Aarn a copy of this thread as it would be good for some input from the designer of these packs. Seeing a picture of these packs and actually trying out one are 2 different things. Hopefully he will respond in time. Just for the record I do not use an Aarn pack when doing short walks, but use a frame less pack and light gear.

My Aarn pack is more comfortable than my day pack even though it is heavier so I now use it for day walks, without the front pockets. It's nice not to have to squeeze everything in, too.

[Taurë-rana]

I walked up Mt Montgomery today with 22kg in my pack which is about 43% of my body weight. It hurt like going up any mountain used to before I got fitter, and I stopped fairly often, but I took 1 hour and 50 minutes there and back and the "official" time for the return walk is 1.5 or 2 hours depending on where you look. I was pleased to find that once I got to the top and took the pack off, I felt fine, and now I'm OK, but have twinges in a couple of muscles. A 2 hour walk is one thing, but I think that unless I keep training over short distances with that sort of weight I would be asking for trouble carrying it on a long trip. However I suspect that with continuing training this would change. This is nothing to do with "Oh, I'm carrying that much, it must be too much" but more to do with just how my muscles felt carrying that sort of weight.

I really don't think I could have carried that weight as easily if I had a normal pack - being able to walk upright with very little pull on the shoulders makes things much easier. The only place I felt the weight was in the leg muscles which were pushing me up or holding me back coming down. I don't feel any restriction on my breathing with the Aarn pack but it probably is a bit warmer. I wouldn't say it's a huge amount though.

As a consequence of that little training walk I'm going to try to keep my total pack weight under 18kg for my next walk, so hopefully I'll be able to enjoy the walk without just enduring it. 15kg would be even better of course, and "under 10kg" would be wonderful, but then I'd freeze to death!

By the way, I have no association with Aarn, but want to give credit where it's due.

[corvus]

I walked up Mt Montgomery today with 22kg in my pack which is about 43% of my body weight. It hurt like going up any mountain used to before I got fitter, and I stopped fairly often, but I took 1 hour and 50 minutes there and back and the "official" time for the return walk is 1.5 or 2 hours depending on where you look. I was pleased to find that once I got to the top and took the pack off, I felt fine, and now I'm OK, but have twinges in a couple of muscles. A 2 hour walk is one thing, but I think that unless I keep training over short distances with that sort of weight I would be asking for trouble carrying it on a long trip. However I suspect that with continuing training this would change. This is nothing to do with "Oh, I'm carrying that much, it must be too much" but more to do with just how my muscles felt carrying that sort of weight.

I really don't think I could have carried that weight as easily if I had a normal pack - being able to walk upright with very little pull on the shoulders makes things much easier. The only place I felt the weight was in the leg muscles which were pushing me up or holding me back coming down. I don't feel any restriction on my breathing with the Aarn pack but it probably is a bit warmer. I wouldn't say it's a huge amount though.

As a consequence of that little training walk I'm going to try to keep my total pack weight under 18kg for my next walk, so hopefully I'll be able to enjoy the walk without just enduring it. 15kg would be even better of course, and "under 10kg" would be wonderful, but then I'd freeze to death!

By the way, I have no association with Aarn, but want to give credit where it's due.

T-a,
With respect 22kg for a couple of hours even at your weight and age is doable however add a couple or three hours and you will find your limits(with any sort of pack) especially when you have no choice but to go on as people are depending on you.
So I would bear in mind that 30% of bodyweight should be your maximum targeted pack weight ,looking at ways to reduce this without compromising comfort and safety
corvus

[Taurë-rana]

T-a,
With respect 22kg for a couple of hours even at your weight and age is doable however add a couple or three hours and you will find your limits(with any sort of pack) especially when you have no choice but to go on as people are depending on you.
So I would bear in mind that 30% of bodyweight should be your maximum targeted pack weight ,looking at ways to reduce this without compromising comfort and safety
corvus

I totally agree