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Posture Columns

ELIMINATING THE BACKPACK STOOP


Your posture under load is determined by the horizontal distance between the center of gravity of your load and the center of gravity of your body.

If these 2 centres of gravity coincide horizontally, no leverages are created on your body and you stand perfectly upright. The forces on the body are just the weight itself. This explains the popularity of carrying load on the head in Africa, Asia and South America. We can say that the centre of gravity of load and the body are aligned on the vertical axis.

However, if the 2 centers of gravity are not on the same vertical
axis, then the offset load creates leverages which increase the forces acting on the body above those caused by the weight alone. The greater the distance between the 2 centers of gravity, the greater the leverages on your body. The leverages concentrate and magnify the forces acting on the body. The scale and effect of these forces on the body are shown in the diagrams below.

Aarn Bodypacks solve the postural problems of backpacks and result in a natural upright posture. This explains the Sports Science findings of greater energy efficiency and the reduction of body pain using Bodypacks.
BACKPACKS HAVE 4 BIOMECHANICAL FLAWS
  1. Backpacks force you to lean forward.
    With all the weight behind, extra leverages are created that increase the forces acting on the body above that of the weight itself. Depending on your torso length, a 16kg load can exert 20-25kg of forces on the body. You lean forward to reduce these forces and keep body + pack weight centered over your feet. These extra forces act on the spine to distort its natural shape. They combine with the forward lean to increase muscle tension throughout the body, especially in the neck, shoulders, back and thighs. Your gait is affected and more energy is consumed with each step.
  2. Backpacks create downward and rearward forces on your shoulders.
    If you loosen the shoulder straps on your backpack the pack falls backwards. To prevent this you keep the shoulder straps tight and brace your shoulders forward. Backpack wearers often push the shoulder straps forward with their hands in an attempt to offset the backwards pull on the shoulders. This force consumes energy and tires your body. Even the best hipbelt cannot alleviate this situation.
  3. Backpacks place weight on the back of the hips - and none on the front.
    With no counterbalancing weight on the front of the pelvis, a rotating force is created around your hip sockets pushing the pelvis downwards at the backside. You unconsciously use muscle tension to resist this force. This is one of the reasons that lower back pain is common in people carrying heavy backpacks.
  4. Backpacks act as a lever on your back making body movements unwieldy.
    Because the center of gravity of the load is well behind that of your body, the load resists the natural flow of body movement. This effect is most noticeable in sports that require a lot of body movement such as skiing. Your balance is completely altered by your pack and once a ski turn is initiated, the load wants to keep on swinging around reducing your control and jeopardizing your balance.
AARN BODYPACKS ELIMINATE THESE FLAWS
  1. Aarn Bodypacks maintain your natural upright posture.
    By choosing the largest volume Balance Pockets available for your Aarn pack model and by packing your heaviest most compact items in these Pockets and your light bulky gear in the pack, you can achieve a naturally balanced load, where the load is balanced around your center of gravity. Now your posture is unaltered when you put the pack on -- there is no forward lean. With the weight balanced front and back no leverages are created on the spine. The forces on the body are only vertical, consisting of the weight alone (16kg).
  2. Aarn Bodypacks eliminate the rearwards force on your shoulders.
    Just as the pack wants to fall backwards away from your shoulders, the Balance Pockets want to fall forwards. The 2 forces cancel each other out so there is no rearwards pull on the shoulders- any load on the shoulders acts vertically down only. This can be reduced to zero by loosening the shoulder straps so that all the weight is taken on the hips. Then the spine is no longer under compression and the shoulder straps act as load locators rather than load bearers.
  3. Aarn Bodypacks evenly distribute the weight on the hips.
    The connection of the front Balance Pockets to the shoulder straps is a sliding connection so that none of the weight in the Pockets goes onto the shoulders. It is all transmitted onto the front of your hips by the Pocket frames. This balances the load of the pack on the back of the hips, eliminating the rotating force on the pelvis. The pelvis stays level without muscle tension, eliminating strain in the lower back.
  4. Aarn Bodypacks allow fluid body movements.
    Balancing weight around the body’s center of gravity is the foundation for natural body movement, natural balance and load stability. For free and fluid movement to be possible under load, the harness of the pack and Balance Pockets must cooperate. Our patented flow motion systems interlink the harness parts allowing your torso to move and twist freely while the load to remains centered and stable.
TESTIMONIALS

“Aarn Bodypacks are innovative and revolutionary and once you’ve experienced one all other packs will fade into insignificance. During my 45 years of tramping, climbing and hunting I have used many packs including the latest ergonomic designs. My experience with Aarn Bodypacks has changed all my previous perceptions of comfort. If I thought the others were comfortable, the Aarn Bodypack by comparison is pure luxury. I have never used a more comfortable pack—it fits your body like a glove. The Balance Pockets reduce a considerable amount of strain and are extremely useful for accessing items while on the move. I would thoroughly recommend an Aarn Bodypack to anyone who wants to experience the pinnacle of tramping or climbing comfort. “
Ray Goldring, NZ Mountain Safety Organization

“ The Porsche of packs”
Patrick Rottiers, CEO, PROconsulting International, Christchurch, NZ

“It is hard not to be evangelical about a product that works so well. It’s hard not to gloat when you pass someone bent over with a big pack.”
Phil Robinson, New South Wales, Australia

“I think the pack is tremendous! It’s the first pack I’ve had that really does what it is supposed to. I had back surgery six years ago. Part of a disc in my back was removed. I don’t have any back pain with my Aarn pack as I always had with other packs. Backpacking is the love of my life. I have had one of the best known, highly rated and most expensive internal frame packs on the market. This one surpasses that in terms of comfort. There was no discomfort in either the shoulders or the hips.”
Dr. Jan Lemon, Neuropsychologist, Boulder, CO, USA.

“Bodypacks virtually eliminate postural stress on the torso and shoulder girdle. My kinesiological tests on a patient who had back surgery showed no stress induced by using the pack”
Jay Wilson, D.C., USA, Chiropractor and Backpacker

“Last weekend we went up the Croesus Track with my old pack. Within about an hour, I was starting to get my usual pain across the right shoulder blade that I’ve become accustomed to whenever I use traditional backpacks and which I don’t get when I use an Aarn Bodypack. I began tramping 26 years ago and have gone through 4 backpacks over that period. Your Bodypacks I have found the most comfortable and I can’t understand why anyone who is planning to purchase a pack would buy any other brand.”
Chris Leaver, Vice-President, Peninsula Tramping Club, Christchurch, NZ

“Bloody fantastic, would not go to other designs”
Anne Griffin, Kangaroo Flat, Australia

"Recently my husband, Joe and I completed 462 kms. on the northern section of the Bibbulmun Track in W.A. I was carrying my Featherlite Freedom pack and Joe was carrying his Natural Balance pack. I carried about 14 kgs and Joe carried up to 18 kgs.
We are both very experienced walkers but our age is beginning to limit us. (We are 73 and 75) We found walking with our Aarn packs allowed us to walk an average 20 kms a day without sore shoulders, sore backs. We had plenty of energy left over at day's end to set up camp, cook our evening meal and after a good night 's rest be ready for the pleasures of walking the next section. Other walkers we met were very interested in the design of our packs and I feel that we are proof that you have got your design principles right.
Thank you for your Bodypacks which have enabled us to realise our ambition of becoming "end-to enders" - we have now walked all the way from Perth to Albany a distance of 960 km".
Beth and Joe Gilks, WA, Australia

"I’m on the Te Araroa trail. I love my Balance Pockets and after 830km - still no sore shoulders/neck etc. Often I don’t bother to take my Bodypack off when having a break because everything is easier to access when it’s on. Great having camera, food, water etc so close to hand.
I have regular massages at home & always my massage therapist finds aches & pains in my neck & shoulders - whether I have been tramping or not. I had a massage en route having walked 500kms - plenty of aches & pains in my legs & feet but NOTHING in my neck & shoulders - awesome. I think its often easy not to notice what is not happening (no discomfort) - but reading of & talking to other trampers & their rubs & aches I know its BLOODY AWESOME that I have none associated with my Bodypack".
Wendy Hare, NZ

"I always quite enjoyed going tramping but my pack always felt like such a weight on my back and shoulders that I wasn't that keen on multi-day tramping. I had tried various brands of packs but they all felt the same to me.
We both agree that after 8 years of intensive use, we are thrilled with our Aarn packs. The packs make carrying weight comfortable and weight of the pack centers through your body - you can almost forget you have a pack on your back compared with other packs we have had in the past.
The convenience of the Balance Pockets in front to access gear/food while walking and the inner waterproof pack liner are brilliant features too.
This pack has revolutionised my tramping. I have tramped further and higher than I ever thought possible and much of that has to do with the Aarn packs I am using."
Helena & Stuart Gane, Auckland, NZ

"I thought that the shoulder–pain associated with carrying a heavy pack was an inevitable by-product of trampling- a necessary evil in order to enjoy the outdoors. Even with good packs my shoulders would hurt. Putting more weight on the hips did not help because I still had to hold the pack forward.
I had no shoulder pain on my first multi-day tramp with an Aarn Pack, despite carrying my normal weight of 18-20 kg. Great design and great attention to detail!"
Stefan Meyer, Nelson, NZ

"Thank You, thank you, thank you so much. I just summited Mt. Kilimanjaro on Sept 3rd thanks to your gear. The other trekkers laughed at my Aarn Bodypack, mainly my Balance Pockets until they saw I could hike with more weight and longer. They stopped laughing when I didn't have sore shoulders or back and they did. I carried my pack everyday except 1/2 of summit day. There was only one other person, a woman, who carried her pack the whole time. With the Pacer Poles you guys advised me to buy, my arms didn't hurt, neither did my hands like the other trekkers did. The guides told me I was strange and I looked strange and I told them whatever it takes. Only 1/2 of our group got to the top, I was the third one to summit of the 7 who made it. A huge thank you!!!"
Jude Brown, Melbourne, Australia

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