(HealthDay News)—Backpacks can cause back pain and injury if they are too heavy or don't offer enough support.

Keep these guidelines in mind when choosing and wearing a backpack, courtesy of the National Safety Council:

• Always wear both straps, so that the weight is distributed across both shoulders and evenly across the back.
  
  
• A backpack should always be centered across the middle of the back.
  
  
• Try not to overload the backpack. Keep it from getting too heavy.
  
  
• Place the heaviest items closest to the back.
  
  
• When lifting the backpack, bend at the knees and lift with your legs.