By Marilyn Miller von Foerster PT, MA
The International Ergonomics Association defines Ergonomics or Human Factors as follows:
“Ergonomics (or Human Factors) is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance.” Ergonomics is employed to fulfill the goals of health and safety, and productivity.
The incidence of backpack-related pain and injury continues to rise and has reached epidemic proportions. Additionally, what we see is probably just the tip of this iceberg, as kids underreport pain, and many parents discount the pain reports they do get, because “they are young” and they see no alternative.
Conventional backpacks used as schoolbags adversely affect the health, safety and productivity of developing schoolchildren, in clear opposition to the goals of ergonomics. They are off-axis, posterior-loading systems, causing the body to compensate with postural distortion. It is postural distortion which is chiefly responsible for chronic musculoskeletal pain. Any load applied off-axis is unhealthy for this reason. The postural distortion will continue unless the load is aligned with the body’s axis, in obedience to the laws of physics and physiology.
As backpack use for school has become widespread, numerous articles and programs have offered instruction and guidelines in “backpack safety” and many manufacturers claim to offer “ergonomic backpacks.” These guidelines, and even legislation, focus on limiting the weight put in a conventional backpack, an important consideration if this system continues to be used. It will reduce some symptoms, but the chief problem of postural distortion is not addressed effectively.
The term orthopaedic literally means “straight child”. It is only during the growth period that one can affect alignment of bones with mechanical means other than surgery, and it is only during the growth period that bones can naturally build density, a lifetime investment.
Therefore, unloading the body is not necessarily a healthy alternative for developing bones. Bones require daily muscle/bone resistance during the growth period in order to build density. Our young people are getting less and less activity and no posture training. Carrying books may be their only opportunity for adequate exercise to increase bone density and prevent osteoporosis, the leading cause of fractures in adults, and increasingly seen in children. The load can be their friend and train good posture, when carried in healthy alignment.
Switching to a rolling backpack is a short-term remedy for discomfort, not a posture-training or bone density solution. A rolling backpack is actually heavier and more awkward when carrying is required (busses, stairs, irregular surfaces).
The safety and health hazards inherent in school use of the conventional backpack — originally intended for mountain recreation, not as a school bag or everyday bag — compelled me to design a healthy alternative for school or everyday use: the BackTpackⓇ.
HEALTH AND SAFETY CONCERNS with use of a conventional backpack:
- POSTURE DISTORTION: commonly seen forward head, kyphosis (rounded spine), rounded shoulders, anteriorly tilted pelvis, hyper-extended knees. Poor foot alignment.
- PAIN AND INJURY:to back, neck, shoulders from poor posture, poor body mechanics: twisting and forward bending. Need for frequent removal, or must sit with poor posture and load on spine.
- INJURY TO OTHERS: user is unaware of posterior bulk of backpack; can easily knock others down when turning quickly. Trip hazard when left on floor.
- POOR SECURITY: accessible to those behind you, not to you. Must remove to access items or to sit down; difficulty in running with it on.
- BIKING INSTABILITY, POOR POSTURE, AWKWARD OR NO ACCESS:top-heavy, must remove for access; encourages kyphosis, cervical hyper-extension causing neck pain.
- INCREASED WEIGHT OF LOAD INCREASES POSTURAL DISTORTION: and associated pain.
- EMERGENCY EVACUATION CONCERNS: classroom floor obstacles, speed, access, uphill running difficulty (Tsunami evacuation), danger to others in crowd when turning, etc.
- BALANCE DISTURBANCE RELATED TO POSTERIOR LOADING
It is a neuromuscular training fact that when resistance is applied against a given direction of movement, that movement is strengthened and trained. This means that resistance applied consistently over time to the front of the shoulders, as by the straps of a loaded backpack, will train a forward head and forward lean with rounded shoulders. To train upright posture, we must load the body on its vertical axis, i.e., the book on the head, or a balanced bilateral load.
It is possible to correct the habitual postural distortion trained by a posterior loading system by applying the load in alignment with the vertical axis instead of on the back. If we apply these clinically sound principles to the everyday loading system of students, we will train their lifelong postural habits for musculoskeletal health.
SOLUTIONS FOR HEALTH AND SAFETY that the BackTpack offers:
- POSTURE DISTORTION IS ELIMINATED. Spine is loaded axially. No leaning; response to load is vertical posture.
- REDUCED PAIN AND INJURY: Reduced or eliminated with postural training system of axial loading and the ability to sit with BackTpack on with load transferred off spine and shoulders onto “LAP-STRAP.” Since compartments are always accessible, and the wearer can sit unloaded with bag on, there is no need to frequently take the bag off.
- NO INJURY TO OTHERS from user being unaware of posterior projection: BackTpack wearer is always aware of personal space related to bag he/she is wearing and can accommodate space so as not to impose it on others’ safety. Since BackTpack can word while seated or draped on the chair, the tripping hazard is eliminated.
- PERSONAL SECURITY, CONTROL OVER BELONGINGS: The wearer’s items are accessible only to the wearer. The bag does not need to be removed for access or when sitting. Tripping hazard is eliminated.
- BIKING STABILITY, POSTURE, ACCESS: BackTpack provides a lower center of gravity, is a balanced load, and compartments are easily accessed. When in the forward lean position, the load is applied to the body in posterior-to-anterior direction against the spine (not from shoulders), promoting a neutral spinal alignment of thoracic spine and neck.
- WEIGHT OF LOAD DOES NOT AFFECT POSTURE: Since the BackTpack loads axially, there is no postural distortion with increased load. Loading this way trains upright posture. The limit of the load increase is a matter of comfort to the wearer. Some or all of the load can be transferred to the hips via the optional hip loading system provided in the design.
- EMERGENCY EVACUATION: BackTpack remedies all of the safety issues mentioned. BackTpacks do not need to be removed for sitting — no trip hazard — and can even remain on the chair when the wearer gets up. The wearer has balance and mobility for rapid evacuation. Turning does not pose a hazard to others.
- NO BALANCE DISTURBANCE FROM LOAD: Balance is reinforced with axial, bilateral loading.
Based on over 30 years of evidence, backpacks continue to cause postural distortion, pain and injury when used as a daily school bag in spite of “backpack safety” programs and guidelines, and claims of “ergonomic” design. Using BackTpack as a school bag effectively addresses the issues contributing to such problems. BackTpack is truly ergonomic.
If students insist on using their backpacks for school, they and their parents must be made aware of the long–term physiological effects and how best to mitigate them with appropriate exercises, training in posture and body mechanics, and to be informed of healthy alternatives for carrying their supplies. Medical professionals can do their part in combating this epidemic by informing the public about these safety issues and about what makes a healthy choice when investing in a child’s school bag.
What is an “Ergonomic Backpack”?
By Marilyn Miller von Foerster PT, MA
577 Bonnie Court NW
Salem, Oregon 97304