Students in middle and high school often carry heavy books to and from school. A backpack that is too heavy, or that is carried improperly, can cause medical problems. Packing and wearing a backpack properly can lessen the potential for pain and injury.
According to the American Physical Therapy Association, a student's backpack should not weigh more than 15 percent of his body weight. A 120-pound student's book bag should weigh 18 pounds or less. A survey conducted at Simmons College in Boston found that 55 percent of children surveyed exceeded the recommended 15 percent.
Backpacks are a better option than one-strap shoulder, one-strap athletic or messenger style bags for carrying books and supplies. The weight of a two-strap backpack is more evenly distributed across the student's body, putting the body in a better mechanical advantage. Carrying all the weight of a book bag on one shoulder pulls that shoulder down, putting the back in an awkward position, and also can strain the opposite shoulder.
A heavy backpack worn over one shoulder may cause students to lean to one side, causing their spine to curve away from its normal alignment which can lead to strain, pain and postural adaptations that lead to spinal compression and improper alignment.
Students can prevent spine curvature, rounded shoulders and other injuries by using both straps and distributing the weight of their backpacks evenly across both shoulders.
Keep in mind, however, that two-strap backpacks that are overloaded or not used properly can cause issues, too.
Heavy book bags put kids off balance, positioning them in an awkward posture, in turn increasing their chances of lower back pain. It is best to use a traditional two-strap book bag with wide, padded shoulder straps, lumbar padding and a belt around the waist.
The bottom of the backpack should rest in the contour of the lower back and sit evenly in the middle of the back, not sag down toward the buttocks.
An ergonomic study conducted at Auburn University reported that book bags that are too heavy for students may threaten developing spines. Of the children who participated in the study, more than half suffered from muscle soreness and back pain, while others suffered from numbness and shoulder pain.
Signs that a book bag is a problem include:
The student has to lean forward to carry it;
The student has back, neck or shoulder pain;
The student struggles to get the backpack on or off;
The student has trouble maintaining their balance;
The student feels numbness or a tingling in the arms, hands or fingers
In conclusion, traditional two-strap book bags worn correctly with wide padded straps, lumbar padding, a belt around the waist, and loaded to no more than 15 percent of the student's weight is the best book-carrying option to maintain correct posture. When worn correctly and not overloaded, some of the strongest muscles in the body will work together to hold the body in optimal alignment and prevent potential injury.
Horne is a physical therapist at Jersey Shore Hospital. She may be reached at 398-3111.