Introduction

Background and Review of Literature

Across the nation, millions of students are racing out to the school bus or scurrying to their classes with backpacks slung over their back. While carrying a backpack to school each morning might seem harmless enough, it can cause some painful back and neck problems that can last a lifetime for students who don't carry their backpacks properly.

  Figure 1: Kids with Backpacks

Figure 2: The Spine and Vertebrae 

               The World Book Encyclopaedia defines the spine as “the part of the skeleton that extends down the centre of the back.”1  It protects the spinal cord and plays a major role in posture and movement.  It is made up of a column of 33 bones called vertebrae.  The vertebrae consists of 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal vertebrae.

These bones are “held in place by muscles and strong connective tissue called ligaments.”2  “In between the vertebrae are disks made of cartilage that act as cushions between the bones.”3  The disks absorb shock and enable the spine to bend.  Your spine also has a slight curve.

Figure 3: The Spine Relative to the Body

             Knowing how to wear a backpack is essential in everyday life.  A backpack should be “sturdy and appropriately sized, have padded shoulder straps, and have waist straps.”4 Padded shoulder straps avoid pressure on the nerves around the armpits and waist straps help stabilize the load.  The load should not exceed 15% of the child’s body weight.  “A backpack that’s too large will sag towards the buttocks, stressing the child’s lower back and shoulders.”5  Also, a backpack that fits poorly or is overloaded can cause pain, poor posture, and red marks from straps.  Facing the backpack before you lift it, and lifting your legs, not your back is recommended.

                                                                             Figure 4: Children Wearing Backpacks

Conditions

The improper use of backpacks can have serious effects on the human body.  “Hauling a heavy backpack over one shoulder everyday may cause serious postural misalignments”6 which can trigger a condition called vertebral subluxation.  Vertebral subluxation causes neck and back pain, headaches, and osteoarthritis.  Also, “carrying a backpack alters the mobility of spinal bones and can lead to restricted movement-a risk factor for pain.”7 Furthermore, backpacks change the fluid content of intervertebral discs.  This is a risk factor for disc herniation and osteoarthritis.    These conditions can effectuate all sorts of problems such as scoliosis which occurs when the spine curves sideways.  When the thoracic vertebrae bends forward this is known as kyphosis, or hunchback.  This condition often affects elderly people.  In addition is the condition lordosis, or swayback, which happens when there is "an exaggerated curvature of the lumbar vertebrae”8.  This condition is usually seen in overweight people and pregnant women.  Most damages of the spine are in the cervical and lumbar regions.

What is and What Will Happen

          “Scientific research reveals an alarming danger associated with improper childhood backpack use.”9  There has been an increase in back pain from ages 11-16.  “By the end of their teen years, close to 60% of youths experience at least one low-back pain episode”10 which may be due to incorrect usage of bags.  According to the U.S. Department of Human Health and Services, back pain leads to more than 19 million doctor visits per year.  Furthermore, the “Consumer Product Safety Commission (CPSC) estimates that 7,277 emergency visits each year result from injuries related to book bags.”11  The CPSC also reports that backpack-related injuries are up 330% since 1996.  But there is hope.  Manufacturing companies are creating more comfortable backpacks to suit the needs of today’s society and new inventions have been introduced including the ‘Bungee-Powered Backpack.’  This unique backpack is like a toy slinky.  It bounces up and down on bungee cords instead of pounding the shoulders and back of the wearer.  But why?  Well, when people walk their hips move up and down as much as seven centimetres, which normally causes a backpack to bob up and down and add additional force.  “A 50-pound load, for example, can slam down with 80 pounds of force when a person is walking and 150 pounds when running.”12  Moreover, it is “designed to keep a load level with the ground during motion and, therefore, neutralize the vibrating force of walking or running with a heavy pack.”13  The load uses a system of pulleys and bungee cords, “allowing it to slide up and down on a mounting of metal rods.”14  “As a person’s hips rise, the mounting raises as well, but the bungee cords let the load dip down, limiting its movement.”15  This device reduces the maximum force on the wearer by more than half while walking and lessens up and down motions by more than half when walking.