Tips on safe backpack use

On any given day, hikers, working adults and about 40 million teens carry backpacks. But load them up too heavily or wear ones that don't fit properly, doctors warn, and you could be risking injury.

"Backpacks weighing more than 15 pounds that are slung over a shoulder produce an imbalance in the rib cage," said Dr. Gerard W. Clum of the Foundation for Chiropractic Progress. "This type of repetitive strain can also initiate arm and hand numbness, headaches or backaches."

Here are tips to avoid injuries caused by backpacks.

•Avoid carrying more than 10 to 15 percent of body weight.

•Distribute weight evenly.

•Wear both shoulder straps unless it's a one-shoulder pack.

•Select packs with heavily padded shoulder straps and lumbar support.

•Bend knees when lifting a heavy pack.

•Carry only what's needed. This story is provided by North American Precis Syndicate Inc.