Image: Bungee backpack
Lightning Packs
University of Pennsylvania researcher Lawrence Rome models the bungee-equipped backpack he and his colleagues developed.
msnbc.com staff and news service reports
updated 12/20/2006 3:16:35 PM ET 2006-12-20T20:16:35

Carrying heavy loads could become easier thanks to a new ergonomic backpack that uses bungee cords to take the strain off the shoulders and joints, scientists said Wednesday.

The cords suspend the load in the pack so it stays at the same height from the ground while the wearer is running or walking, thus reducing the risks of muscle and joint problems.

Its designers said it will allow users to carry an extra 12 pounds (5.4 kilograms) while expending the same amount of energy as when carrying a normal backpack.

“For the same energetic cost, you can either carry 48 pounds in a normal backpack or 60 pounds in a suspended ergonomic backpack,” Lawrence Rome of the University of Pennsylvania said in a written statement. “It is like carrying an extra 12 pounds for free.”

The backpack, which was designed for soldiers and emergency workers, could be useful for children and hikers.

“Being able to move at relatively high speeds is crucial for many professions as well as in some athletic competitions and recreation,” said Rome, who collaborated with researchers at the Marine Biological Laboratory in Woods Hole, Mass.

Overloaded backpacks carried by schoolchildren are an “internationally recognized” public health problem, the researchers pointed out. The bungee-cord backpack could help prevent injuries to children who carry backpacks — or, in another application, it could allow emergency personnel to run more easily while carrying heavy equipment.

In most traditional backpacks, the load is attached to the frame of the pack, which is strapped tightly to the body. As a person walks, it moves in line with the hip.

The new pack, which is described in Thursday's issue of the journal Nature, reduces the vertical displacement of the load.

“What is striking about our ergonomic backpack is that one can feel the 86 percent reduction in force with each and every step,” Rome said.

Last year, Rome and his colleagues published research on a related backpack technology that used the up-and-down displacement of the load to generate electricity. Rome told MSNBC.com that the power-producing backpack used springs to capitalize on the jiggling movement, while the newly developed backpack used the bungee cords to minimize the jiggling.

The scientists have formed a company to produce the backpacks — known as Lightning Packs — and are now working on a lighter, small version.

This report includes information from Reuters and MSNBC.com.

© 2013 msnbc.com

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