The American Academy of Orthopedic Surgeons is recommending students get into shape before they start carrying their backpacks again. The academy warns doctors are seeing more young people with back and shoulder problems.

Dr. Angela Smith, an orthopedic surgeon, says the combination of unconditioned trunk muscles and a heavy back pack is the cause of a lot of the shoulder and back pain doctors are seeing.

"Much of the back pain in school age children is now due to weak trunk muscles and poor flexibility," says Smith.

She says even if you play soccer five days a week, you still don't have the necessary strength and agility to carry heavy packs. Smith recommends doing back and abdominal exercises.

The academy has also released recommendations concerning the type of pack students and parents should look for:

• choose one with wheels if the school allows it
• buy a camping-quality pack with the appropriate structures built in for weight
• make sure shoulder straps are padded and use both shoulders while carrying the backpack
• look for a waist/hip strap so the weight is distributed evenly

There are also suggestions for how to carry the pack:

• make sure the weight is carried close to the body
• use the correct lifting technique: bend with both knees when picking up a heavy pack
• place the heaviest items close to your back
• neatly pack the backpack
• make frequent trips to your locker to replace books

Smith says shoulder bags are fine but only if they carry small, light items.

She warns anyone experiencing persistent pain, numbness or tingling should see a doctor.