Sitting position can influence risk of whiplash

Women run a three times greater risk than men of incurring a debilitating injury in a rear-end collision. This is partly due to differences between the sexes regarding sitting position. This has been shown by Bertil Jonsson at Umea University in Sweden.

Neck injuries among vehicle drivers as a result of being rear-ended remain a major problem for victims and cost insurance companies and society huge sums. Bertil Jonsson's dissertation shows that women run three times the risk of incurring debilitating neck injuries compared with men. For both women and men, the findings show that the driver's seat entails twice the risk compared with the front passenger seat.

The dissertation elucidates differences in the sitting position between women and men in the various seats of a car that can provide a partial explanation of the risk differentials observed. Women drivers adjust the driver seat differently than male drivers do: women sit higher and closer to the steering wheel and have the seat back more upright.

Men have a greater distance between the back of their head and the neck support (so-called backset) compared with women, both when the car is stationary and when driving. If the driver holds his/her hands on the upper part of the steering wheel, the backset distance also increases to the head support compared with the passenger position. High backset values are a known risk factor for neck injuries in rear-end collisions.

The scope of the neck to move in a horizontal backward direction (so-called retraction) is different between the sexes, but it is also affected by sitting position. A slouched posture entails a greater distance to the head support and also reduces the scope for free movement backward (retraction). When this scope is exceeded, injuries probably occur.

Current crash dummies used to develop vehicle seats and neck supports, for instance, are geared to men of normal size, but not to women. This is especially true in regard to height. Nor does testing methodology take into consideration differences between the sexes, or differences in sitting position between the driver's seat and the front passenger seat.

The dissertation shows that further research is needed regarding sitting position and the risk of injury. Test methods need to be developed for rear-end collisions, as well as a female crash dummy. The findings provide a foundation for the development of new test methods and protective systems in future vehicles that could reduce the risk of neck injury in rear-end collisions.

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