BALANCE - Natural Upright Posture
ELIMINATING THE BACKPACK STOOP
How a load carrying system like a day pack or backpack affects your posture is determined by the horizontal distance between the center of gravity of your load and the center of gravity of your body.
If there is no horizontal distance between these then the 2 centers of gravity are on the same vertical axis. This means that 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.
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 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 body packs and why Aarn's product line is considered the best hiking daypacks and backpacks in the world. We offer the lightest backpack that also evenly and safely distributes weight around your body while meeting your center of gravity for the best results.
BACKPACKS HAVE 4 BIOMECHANICAL FLAWS
- Backpacks force you to lean forward.
With all the weight behind, even the best day backpack creates extra leverages 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.
- Backpacks create downward and rearward forces on your shoulders.
If you loosen the shoulder straps on your backpack the pack falls backwards. That's true for even the lightest backpack. 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. The best hiking daypack can when it's correctly distributing the weight, though.
- 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.
- 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
- 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). This is why our lightest backpacks can handle heavy loads without tiring you out.
- 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. This action is what make Aarn the best day backpack available for comfortable load bearing.
- 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.
- 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. How we do this is explained in detail here.