Backpacks are standard load carriers for people of all ages, especially school children. Now that schools are open and backpacks remain a popular carry-all school bag for kids, let us make sure that they are protected from carrying more than their share of loads.  

Studies have previously described the impact of the forces exerted by backpacks on load distribution, back pain, and gait. This study describes the effect of forces exerted by specific backpack weights.

Backpack studyPeople everywhere have struggled to assess the impact of objects in a backpack to the body in general, and to the spine in particular. Backpack use is associated with back pain, intervertebral disc compression, neck pain, altered posture, altered walking mechanics, and plantar foot pressure.

Previous studies have suggested a safe load of 10% bodyweight in children and adolescents, 13% and 15% in young adults, and 15-20% in college-aged adults. This study focuses on the force generated to the spine.

The first affected by overloaded backpacks are the ligaments. When the ligaments are stressed and inflamed, there is a probable loss of side-by-side range of motion and stiffness. The muscles are also stressed and inflamed. Stressing a muscle makes it stronger. However persistent eccentric loading leads to intractable pain. The disc spaces are also eccentrically loaded. With persistent eccentric loading the process of wear, tear, and degeneration proceeds. In worst cases, surgery may be needed.

What You Need to Know

One book is equivalent to seven books to your spine. Force magnifiers are identified at 7X in neutral spine, and 12X in 20 degrees of forward posture.

Pack only what’s necessary. People tend to overpack their backpacks. Remember that each heavy item have consequences to the spine.

Use digital textbooks. Digital textbooks are lighter and do not transmit forces on the spine.

Embrace neutral alignment or proper posture. Proper posture is the position of ears above the shoulder, angel wings back = chest open. This is the most efficient position. Proper posture means chin being level with the floor, your scapula retracted, and your abdomen firm. Study shows that in neutral alignment which is good posture, the forces on the spine are 7.2X the weight. With just 20 degrees of forward posture or poor posture, the force is magnified to 11.6X the weight. This is a 60% increase in forces.

Wear both straps of the backpack. The forces on the spine are the same with one strap or two straps. Both straps allow for a division of the forces that the spine sees. Similarly, with one strap, one side sees twice the amount of forces.

Keep the backpack close to the body. Closest to the body is the most efficient position for diminishing spine forces

Develop a strong core and legs. The body provides certain inherent muscle shock absorbers. Building the core muscles helps strengthen the body’s force dampeners. Strong thigh muscles help.

This feature is contributed by Dr Kenneth K Hansraj, spinal and orthopaedic surgeon specialising in cervical, thoracic and lumbar procedures for example laminectomies and spinal fusions.