Every day, almost 90% of journeys and 92% of kilometers traveled are made in cars or ground transportation (buses, trucks). For almost 14 millions of us, driving is the primary means of transportation, for journeys to and from work, to the store, and for pleasure. On average, men drive 68 kilometers and women drive 54 kilometers each day. We Australians love our cars. For some Australians, driving a motorized road vehicle is also their job: truck drivers, bus drivers, ambulance and fire trucks, police, taxis etc.

Modern car and truck designs have come a long way in their design over the past 20 years, with better styling, better features, better fuel efficiency and better comfort. But is there any evidence that driving and the design of modern car, bus or truck seats might play a role in causing some of the back injuries that plague Australians each year?

Why is driving different to ordinary sitting?
If your car isn’t moving, then sitting in a driving seat probably isn’t much different to sitting in a padded chair, but as soon as the vehicle starts moving things change. Unlike regular sitting, while a vehicle is in motion the body is subject to different forces: to accelerations and decelerations, to lateral swaying from side to side, and to whole-body up and down vibrations. Also, when driving the feet are actively being used, the right foot on the gas (accelerator) pedal, the left on the brake, and in a stick-shift also on the clutch. When the feet are active they cannot be used to support and stabilize the lower body as normally happens when they are placed on the floor during normal sitting in a chair. There is evidence that the combination of these factors, coupled with the design of the car seat itself, can increase the chance of back problems for some people.

Is driving associated with back problems?

Laboratory research has studied the effects of whole-body vibration when a person is sitting in a car seat. The lumbar spine has a natural resonant frequency of 4-5 Hz , and results show that this natural frequency can be excited by laboratory simulated vehicle driving, and this can lead to high spinal loadings in the lower back, and this in turn could result in greater postural discomfort and an increased risk of low back pain and injury.

A number of research studies have investigated possible associations between driving and back problems, and generally these studies have found significant results.

A recent comparison of drivers in the USA and in Sweden found that in each country 50% of those questioned reported low back pain. Analysis of the possible reasons for this revealed that long-term vibration exposure from driving was among the highest risk factors for neck, back and low back problems. Ano ther recent Swedish study of over 1,000 salespeople found significantly increased risks of neck and low back pain among those who drove long distances and spent a long time each day in their car.

Gender appears to play a significant role in the likelihood of developing driving-related back problems. A survey of over 7000 Parisians found that even though the incidence and severity of low back pain was higher in women, driving was only associated with back problems in men. The importance of driving as a risk factor increased with driving time, and was especially significant for men who drove 4 hours or more each day.

A survey of over 1400 urban transit drivers showed that difficulties with the ability to correctly adjust the driving seat have significant effects on the prevalence of low back problems.

However, it seems that driving need not always increase the risk of back problems. A survey of over 100 members of the Royal Canadian Mounted Police found no statistically significant associations between driving a patrol car and the likelihood of experiencing back pain, which was comparable for drivers and o ther police officers.

Is there an ideal car seat design?

Based on a detailed analysis of information from peer-reviewed scientific journals and texts, automotive engineering reports, and the National Library of Medicine a series of requirements for the optimal car seat design have been developed. Ideally, the optimal car seat should have:

• 1. adjustable seat back incline (100 degrees from horizontal is optimal)
• 2. changeable seat bottom depth (from seat back to front edge)
• 3. adjustable seat height
• 4. adjustable seat bottom incline
• 5. seat bottom cushion with firm (dense) foam
• 6. adjustable lumbar support (horizontally and vertically adjustable)
• 7. depth pulsating lumbar support, to reduce static load
• 8. adjustable bilateral arm rests
• 9. adjustable head restraint with Lordosis pad
• 10. seat shock absorbers to dampen frequencies between 1- 20 Hz
• 11. linear front-back seat travel to allow differently sized drivers to reach the Pedals
• 12. seat back damped to reduce rebounding of the torso in rear-end impacts.

What to look for in a good car seat design when you buy your next car.

It’s likely that most cars on the market today won’t have all of the features listed above that are desirable in the optimal car seat, but some will have more than o thers, so choose wisely. Pay particular attention to the following 5 guidelines that should help you to protect your back when you drive.

1) Car seat comfort
when you sit in the car seat and you have adjusted this to fit your body as best you can does it feel comfortable. If not, then the car seat will probably cause you back discomfort problems if you drive for any length of time. Bounce up and down in the seat to see how it accommodates vibration. Take the car on a test drive.

2) Car seat adjustments
can you adjust all of the features of the car seat that you want to adjust? At a minimum you should be able to adjust:

• Seat distance to accommodate different leg lengths
• Seat height to accommodate different leg lengths
• Backrest angle to sit in ei ther an upright or more reclined position

 

Then you should look for other useful adjustments:

• Seat tilt to angle the front of the seat up or down so that this doesn’t press against the back of your knees
• Lumbar cushion support for the lower back. Look for a car seat that provides you with good low back support that can be adjusted for depth (often the seat has an inflatable cushion) and preferably for height as well.
• Headrest for neck support
• Arm rests that are wide, cushioned and comfortable, and preferably height adjustable.

3) Change your posture
remember to move your posture from time to time. Wait until driving conditions are suitable to allow you to wriggle in the seat to alleviate postural fatigue.

4) Take breaks
driving is tiring work and to avoid driver fatigue and minimize postural discomfort it is good take to fairly frequent rest breaks that allow you to stand up and move around.

5) Seat accessories
you can choose a variety of car seat accessories that may improve seat comfort for you, from fleece covers to soften the seat to bead backrests to provide for some kind of back massage while you drive. Choose whatever you find adds to your driving comfort.