Drivers Beware:
Lumbar Support Can Be Harmful To Your Health!

 

Car Backrests/Headrests: 4 Design Fallacies Causing Back and Neck Pain Driving

by Dennis Zacharkow, PT
© 2014

Fallacy #1: A 25° Backrest Recline is Optimal for Driving.

As evident from many television commercials, the auto industry continues to promote a passive, lounging driving posture with an excessive backrest recline.

An excessive backrest recline of 25° distorts the proper upright relationship of the head, neck, and upper back due to the visual requirements of driving. In order to achieve the proper visibility out the windshield, the driver pulls the head, neck, and upper back forward.1 The resulting distorted posture leads to neck pain, upper back pain, and headaches. In addition, the greater the backrest recline, the more the upper arms are lifted forward to reach the steering wheel, adding further stress to the neck, shoulders, and upper back.

Besides distorting the proper upright relationship of the head, neck, and upper back, an excessive backrest recline also distorts the proper upright relationship of the trunk and pelvis, by displacing the trunk behind the pelvis.1 Driving in such a lounging posture results in a relaxed core, with the driver having the same trunk muscle activity as an unconscious person!

An activated core through proper trunk stabilization is essential for providing an effective foundation for all limb movements.2 The end result is faster reaction times of the right lower extremity at the foot pedals and the upper extremities at the steering wheel. However, a lounging posture with a relaxed core results in delayed reaction times at the foot pedals and steering wheel.

Fallacy #2: New Forward Headrest Designs Improve Driver Safety.

An excessive backrest recline of 25° is also the basis for the flawed, forward headrest (head restraint) design of the last few years.3-5

As a result of the distorted forward posture of the head and neck with the recommended 25° trunk recline, the new headrests need to be designed a significant horizontal distance forward from the backrest, in order to be close to the back of the driver's head.

Unfortunately, for many drivers, these new forward headrest designs actually push the driver's head forward, resulting in neck/upper back pain, headaches, and distracted driving.

In general, the drivers most harmed by the new forward headrest designs are:

  1. Drivers preferring the healthiest and most alert driving posture -- driving with just a slight recline to the trunk, no greater than approximately 5° to 10°.
  2. Thinner drivers with less depth to the trunk. These individuals will be closer to the headrest than heavier individuals with greater depth to the trunk.
  3. Drivers in cars where the backrest has excessive concavity and/or softness in the mid-back region. As the driver's thoracic spine and rib cage sink into these backrests, the relative headrest position will be moved further forward.

Fallacy #3: A Deep, Horizontal Concavity (Deep Bucket) to the Backrest Improves Driving Posture and Comfort.

A slight side to side contouring of the backrest does improve comfort and helps keep the driver's posture as symmetrical as possible. This slight contouring is appreciated most by tall drivers.

However, a recent unfortunate trend in many car models is an excessive horizontal concavity to the backrest. This excessive side to side contouring distorts one's driving posture by rounding the back and shoulders, and restricting diaphragmatic breathing. The greater the horizontal concavity, the greater the risk for neck/upper back, mid-back, and lower back pain.

As Bennett explained back in 1928: "A deep, snug-fitting curve, however, is too confining for comfort. The line across one's back at the shoulders is practically straight, and a curvature in the support here tends to throw the shoulders forward and hinders expansion of the chest and related factors of erect posture." .6

Fallacy #4: Lumbar Support is the Most Important Feature of the Car Backrest for Improving Posture and Preventing Low Back Pain.

Most health professionals agree with the auto industry and advocate the use of lumbar support. Among consumers, lumbar support is synonymous with the words "proper back support."

However, lumbar support does not deserve all this praise, because:

  1. Lumbar support distorts one's driving posture by displacing the upper trunk behind the hips. This moves the driver further away from the windshield and steering wheel. The driver usually adapts to this postural distortion by rounding the back and shoulders, and bringing the head forward. Maintaining this posture when driving increases stress to the neck and upper back.7
  2. Lumbar support results in a protruding abdomen, with a relaxation and overstretching of the deep lower abdominal muscles -- critical postural muscles for both sitting and standing posture.
  3. Lumbar support increases the risk of developing a herniated lumbar disc. This is because the location of lumbar support is too high to stabilize the pelvis when driving. Without firm pelvic stabilization, a major effect of the vibration and road shock from the moving vehicle is a rapid rocking of the pelvis over the ischial tuberosities (sitting bones) .8 This rocking motion of the pelvis localizes the greatest bending motion in the spine to the two lowest lumbar vertebrae: L5 and L4.9 This correlates with the most frequent level of disc herniation being at L5-S1, the second most frequent at L4-L5.

Lumbar support is located too high to prevent the rocking motion of the pelvis, and the resulting stress on the lower two lumbar discs.

How to Prevent the Harmful Effects from the Auto Industry's Fallacies in Backrest/Headrest Design.

  1. Drive with just a slight backrest recline of 5° to 10°. Unlike an excessive backrest recline of 25°, a slight backrest recline will not distort the proper upright relationship of the head, neck, rib cage, and pelvis.

  2. Add lower thoracic support to both correct an excessive forward headrest design and correct an excessive horizontal concavity to the backrest.

    Lower thoracic support elevates and stabilizes the rib cage, elongates the thoracic spine, and moves the upper trunk slightly forward. With the proper thickness of the lower thoracic support, the head and neck are positioned in a stress-free upright posture, with very slight clearance of the back of the head from the excessively forward headrest.

    By elongating the thoracic spine and moving the upper trunk slightly forward, a lower thoracic support will also prevent the driver's thoracic spine and rib cage from sinking into the excessive horizontal concavity of the backrest. As a result, the typical round back, round shoulders posture will be corrected.

    In addition, lower thoracic support provides counter-support for the pressure applied by the upper extremities when steering.

  3. Add sacral support to firmly stabilize the pelvis. A firm sacral support will prevent the rocking of the pelvis when driving, thereby greatly reducing the bending motion and stress on the lower two lumbar discs. Sacral support is the most important feature for preventing a herniated lumbar disc from driving.

    If the car backrest has an adjustable lumbar support, the lumbar support should be reduced to the lowest possible setting before adding sacral support.

    Sacral support also provides counter-support for the pressure applied by the foot to the foot pedals. This additional stabilization is beneficial in preventing fatigue and pain from developing in the lower back/hip musculature.

  4. Remember, the driver's seat is not an easy chair for lounging, but a special "work chair," with the driver being involved in a continuous vigilance task.10

    The resulting "active-alert" driving posture with lower thoracic support, sacral support, and a slight trunk recline (5° to 10°) is called The YogaBack™ Posture.

    The YogaBack Posture activates the elongation reflex of the trunk, resulting in optimal trunk stabilization through proper activation of the diaphragm, deep lower abdominals, pelvic floor muscles, and the lower thoracic erector spinae.7,11

Transforming one's driving posture to The YogaBack Posture is the key to relieving neck/upper back, mid-back, and low back pain -- and the key to faster reaction times at the foot pedals and steering wheel.

For more details on the science behind The YogaBack Posture, go to yogaback.com

References

  1. Zacharkow, D.: ZACKBACK Sitting. Rochester, ZACKBACK International, 1998.
  2. Evans, E.: Ergonomic aspects of the driving position - a postural analysis. In Ergonomics in the Tourist, Agricultural, and Mining Industries. Proceedings of the 22nd Annual Conference of the Ergonomics Society of Australia and New Zealand. Carlton South, Victoria, Australia, ESANZ, 1985, pp. 250-255.
  3. Insurance Institute for Highway Safety (IIHS): A Procedure for Evaluating Motor Vehicle Head Restraints. Issue 3, March 2008. (Available online)
  4. Insurance Institute for Highway Safety (IIHS): IIHS Procedures for Rating Seat/Head Restraints. (Available online)
  5. Zacharkow, D.: New Car Headrests (Head Restraints) Designed Too Far Forward: Hidden Costs are Neck/Back Pain and Distracted Driving. 2013. (Available online)
  6. Bennett, H.E.: School Posture and Seating. Boston, Ginn and Company, 1928.
  7. Zacharkow, D.: Women’s driving posture: an overlooked health issue. Worldwide Spine and Industrial Rehabilitation, 1(2): 5-10, Fall 2001. (Available online)
  8. Branton, P.: Behaviour, body mechanics and discomfort. In Grandjean, E. (Ed.): Proceedings of the Symposium on Sitting Posture. London, Taylor and Francis, 1969, pp. 202-213.
  9. Sandover, J., and Dupuis, H.: A reanalysis of spinal motion during vibration. Ergonomics, 30:975-985, 1987.
  10. Grandjean, E.: Sitting posture of car drivers from the point of view of ergonomics. In Oborne, D.J., and Levis, J.A. (Eds.): Human Factors in Transport Research, Vol 2. London, Academic Pr, 1980, pp. 205-213.
  11. Rathbone, J.L., and Hunt, V.V.: Corrective Physical Education, 7th ed. Saunders, Philadelphia, 1965.

All site contents are Copyright 2002-2017
The YogaBack Company
P.O Box 9113, Rochester, MN 55903   
1-800-SITTING (1-800-748-8464)


  PRODUCTS:
[The YogaBack Company] [The YogaBack for Driving] [ZACKBACK Chair] [Posture Textbook]  
ORDER FORMS:   [YogaBack for Driving Order Form] [Posture Text Order Form]