In the hierarchy of bags, a backpack is a better way to carry life's necessities than a briefcase or shoulder bag, especially for longer periods of time. Wear both straps. Slinging a backpack over one shoulder causes a person to lean to one side to compensate for the uneven weight, curving the spine. Over time, this can cause lower and upper back pain, strained shoulders and neck, and even functional scoliosis, or curvature of the spine.
Teenage girls are especially susceptible to scoliosis.
Older adults need to be weary of osteoporosis. Make sure the backpack is not too heavy. Even when worn properly with both straps, leaning forward to compensate for this extra weight can affect the natural curve in the lumbar, or lower back, region. Extra weight may cause a rounding of the shoulders and an increased curve in the thoracic, or upper back, region. As a result, the person may experience back, shoulder and neck pain.