Can school backpacks influence posture and therefore contribute to osteoarthritis?
By Becky Blaauw.
Becky graduated cum laude from Stellenbosch University in 1995 and has been in private practice in Somerset West for twenty years. She is married to fellow biokineticist Professor Bokkie Blaauw and has two sons. She recently undertook a research project into the effects of heavy school backpacks on children's musculoskeletal systems during their growing years.
Like all parts of the body, the spine is prone to a number of specific diseases. A common disease is scoliosis, a condition that involves curvature or deformity of the spine. Ten in every 200 children develop scoliosis between the ages of 10 and 15. Although boys and girls seem equally affected, the curvatures in females are three to five times more likely to progress into more pronounced postural defects that have longer lasting consequences.
There are two types of scoliosis:
Structural scoliosis involves a curve in the spine which is irreversible, caused by both unknown factors normally found at birth, and known factors such as spina bifida, cerebral palsy or muscular dystrophy.
Functional scoliosis involves a curve in the spine from postural compensation due to gait changes, leg length discrepancies and muscle imbalance. This type of scoliosis can be reversed. For the purpose of the article the scoliosis I refer to is functional scoliosis, which is found in a large percentage of all school-age children, as well as in adults. Many functional curves become fixed as the brain attempts to guard the over-conpensating muscles. This compensation for asymmetric stresses occurs through altering the balance in associated soft tissues and adjacent skeletal structures.
While heavy school backpacks do not in themselves cause structural scoliosis, it is well documented that these bags and the way they are carried cause muscle imbalance and thus contribute to functional scoliosis.
The 21st century has seen many changes in the way schoolbags are carried: from carrying school cases as in generations gone by to carrying backpacks slung over one shoulder, this one-sided carrying of a heavy weight through a good portion of the school day contributes to functional scoliosis and therefore back problems in the future. It was therefore recommended that school children wear back packs, with straps over both shoulders, to equalise the weight carried on the shoulders, thus minimizing back pain and the possibility of future problems. Backpacks have now become the number one choice of bag for today's scholars, used by millions of children worldwide every day. However, it has been found that even children wearing backpacks are still suffering from back-, neck- and shoulder pain.
In most schools in South Africa it is seen as ‘not cool' to wear your satchel with both straps over the shoulders, and it would seem that principals are powerless, or unwilling, to change this damaging culture.
How backpacks can hurt
When carried correctly, in a way that keeps the weight distributed evenly across the back, backpacks are the best way to carry schoolbooks and can even help strengthen the muscles that support the spine. Carried incorrectly by overloading or slinging over one shoulder, the backpack can strain muscles and joints, leading to back and neck pain.
To understand how a heavy or improperly worn backpack can affect a child's spine, it is important to understand how the spine works. Humans are born with 33 separate bones called vertebrae that make up the spine and support the majority of the weight imposed on it. Between the vertebrae are spinal discs that function as shock absorbers and joints, absorbing the stresses placed on the spine.
When more stress is placed on the spine than can be absorbed by the discs, the spine becomes unbalanced which can lead to injury. So for example, a heavy backpack pulling a child backwards causes the child to compensate by either bending forward or arching their back. Slinging a backpack over one shoulder can cause a child to lean too far to the one side to offset the weight. Over time, this overcompensation can lead to poor posture, muscle strain and pain. Further, backpacks with tight, narrow straps that dig into the skin can interfere with circulation and nerve function, causing tingling, numbness and weakness in the arms and hands.
Maximum load in backpacks
Research shows that a child should not carry more than 10-15% of their body weight on their backs. However, an Italian study revealed the weight of the average child's backpack to be 22-27% of their body weight.
When my own son, now 11 years old and weighing 40kg, started complaining of backache, I weighed his school back pack and found that at 10kg, my son was carrying 25% of his body weight on his back. Quite a wake-up call!
Can schoolbags cause later arthritis?
While no long-term studies have been done, it is logical that heavy schoolbags will be a contributing factor to developing osteoarthritis in adulthood. Alignment of the joints is of utmost importance to ensuring equal pressure is placed on all bones, and misalignment causes wear and tear on various parts of the body, ultimately contributing to osteoarthritis.
When the neck has a normal curve, the weight of the head is balanced and neck muscles endure only minimal strain. However, if the neck is straight or in a ‘Forward Head Posture (FHP)' position to counteract the effect of a heavy backpack, constant strain is placed on neck and shoulder joints, predisposing the child to arthritis which can begin even at young ages.
In one recent study, researchers assessed approximately 1000 students aged 12 to 18 from 10 different high schools in Adelaide, South Australia, with and without their school backpacks. When the students carried heavy backpacks, significant changes were visible in their head and neck angle, with the youngest students displayed the greatest posture changes.
Investigating posture backpacks
A study conducted at Blaauw and Partners Biokinetics investigated this matter. The study was to see the effect of an ordinary backpack compared to a newly designed posture backpack on the upper spine of school children. A posture backpack is specially designed to eliminate the load on the child's neck and back, through the use of additional chest and hip straps.
Together with a Grade 9 school pupil, who initiated the investigation for a school project, a posture analysis was done on 10 subjects aged 14 to 15 years. Subjects were photographed wearing a posture backpack and a standard backpack, each weighing 7.5kg, and the percentage of body weight carried in their backpacks was determined as an average of 12% of body weight.
Software called PosturePro was used to calculate a posture number, which is a measure of selected anatomical markers. The posture number is influenced by every aspect of the body's alignment with the ideal posture set at zero. Therefore, the closer the posture number is to zero, the better the posture is. What became evident was that the posture number moved closer to zero when students wore the posture backpack, showing the positive effect that these backpacks have on the child's posture.
The posture backpack had a positive effect on the following aspects of posture:
- Decreasing stresses on the neck vertebrae
- Decreasing the degree of Forward Head Posture (FHP)
- Decreasing kyphosis – the medical condition where a person's upper spine curves forward
It was concluded that the posture backpack has a significant effect in negating the bad effects of carrying heavy backpacks in schoolgoing children, and thus reducing the risk factors contributing to osteoarthritis in the upper spine during adulthood.
From this small study, significant results were determined, and provide a solid basis for a more indepth study to be carried out on the benefits of wearing a posture backpack.
Warning signs a backpack is too heavy
If you notice your child displaying these signs, check to see the weight and type of their school bag:
- Change in posture when wearing the backpack
- Struggling to lift and put on or take off the backpack
- Pain when wearing the backpack
- Red marks on the shoulders
- Tingling or numbness in the arms
Preventing injury when carrying a backpack
- Pack lightly: The combined weight of the backpack and its contents should not exceed 10-15% of the child's body weight. Girls and younger children should aim for the lower end of this percentage range.
- Organize the contents: Pack heavier items closest to the back, and spread items across all compartments so that the weight is evenly distributed
- Use both shoulder straps to distribute the weight evenly across the back. Shoulder straps should be adjusted to allow the child to put on and take off the backpack without difficulty and permit free movement of the arms.
- Tighten the straps to keep the backpack close to the body. The backpack should rest evenly in the middle of the back. Make sure the backpack does not extend below the lower back.
- Use a locker (if available). Don't carry everything needed for the day all the time. And unless that laptop, iPod, makeup bag or, for the little ones, favourite action figure is REALLY needed, leave it at home.
- Squat down, bending at the knees, not at the waist, when lifting or lowering a heavy backpack.
- Do back strengthening exercises to build up the muscles that support the spine.
- Encourage your child to tell you about any pain or other symptoms he or she may be experiencing because of a heavy backpack. Be on the alert for any outward signs of discomfort.
- If your child mentions back or neck pain, pay attention and don't ignore their complaints. If the pain persists, make an appointment with a paediatrician or medical specialist.
- Although a backpack won't cause scoliosis, it can disguise a spinal curve that may be developing. Onset most commonly takes place during the ‘growing years' of 9-15, so be sure that your child is screened regularly for the condition.
- If the homework load seems to be excessive, talk to your child's teacher or school administrators.
- Ensure that the school provides lockers, and allows enough time for students to stop by their lockers throughout the day. If the school does not have lockers, it's time to lobby for them.
- Lobby for the school to introduce a rule that all backpacks must be carried on both shoulders both around the school during the day and on the way to and from school.
- If possible, and if there is a secure locker at school, consider buying a second set of textbooks to keep at home.
- Wear a specially designed posture backpack
Please remember back pain in children that persists for more than 5 days should be seen to by your doctor, physiotherapist or biokineticist.
Enquiries about posture backpacks can be made at Blaauw and Partners Biokinetics: 021 852 7148 or www.blaauwandpartners.co.za
For further reading on this topic, please refer to these publications:
1.Markwicker J, MS PT. Backpack fitting and Posture. November 2'3. www.npioline.org/articles/backpack-fitting-and-posture
2.Sheir-Neiss GI, et al. SPINE (Philia Pa 1976) 2003 (May 1):28(9): 922-930. "The association of backpack use and back pain in adolescence"
3.Neuchwander TB, et al .SPINE (Phila Pa 1976) 2'0 (Jan 1): 35 (1): 83-88. "The effects of backpacks on the lumbar spine in children: a standing magnetic resonance imaging study."
4.Asher A. "Backpacks and back pain – The Links between Backpacks and Back Pain." http://backandneck.about.com/od/childrenissues/tp/Back-Packs-Back-Pain.htm
5.Ramprasad M, et al. Indian Pediatr. 2'0 (Jul 7): 47(7):575-580 "Effects of backpack weight on postural angles in pre-adolescent children."
6.Rodrigues-Oviedo P, et al. Arch Dis Child. 2'2 (Aug): 97(8): 730-732 'School children's backpacks, back pain and back pathologies."
7.Chansirinukor W, et al. "Effects of backpacks on students: measurement of cervical and shoulder posture." www.ncbi.nlm.nih.gov/m/pubmed/11
9.Scoliosis research society. www.srs.org/patient_and_family/kyphosis
10.The effects of school bag design and load – PubMed Mobile. 2'1 www.ncbi.nlm.nih.gov
11.The effects of backpack load placement on posture. 2009 www.ncbi.nlm.nih.gov/m/pubmed/19369727