So there you are sitting in your car waiting for the light to turn green, thinking that your worst problem is going to be getting back to the office before your boss notices that you've just taken a two-hour lunch break. Then, suddenly--
POW! The driver behind you, who was probably busy worrying about exactly the same thing, plows right into your rear bumper. Your adrenaline level shoots through the roof, because some prehistoric instinct tells you that you've just been attacked from behind by a saber-toothed tiger, but that's not your worst problem at the moment. Your worst problem is that a tiny fraction of a second ago you were sitting stock still and now, before you can prepare for it, your torso is moving forward and your head is snapping back. You aren't necessarily moving forward very quickly. The car that nudged your rear bumper may only have given you about a 15-mile per hour (24.1-kilometer per hour) kick and your seat harness (you were wearing one, right?) kept you from getting knocked against the dashboard. But that doesn't mean your body didn't get injured. You just might not be aware of it yet.
The accident we've just described is the single most common kind of car accident there is: the typical fender bender or rear-end collision. And it can lead to the most common (and probably the subtlest) type of driving injury: whiplash.
Whiplash! You're heard that term before, right? You've also heard that it's something you want to avoid, because it causes chronic pain and neck movement problems. If you're old enough, you remember when people would walk around with neck braces as a form of whiplash treatment. (Doctors don't like to do that as much these days, because it doesn't seem to help a lot.) So what do you if you're on the front end of a rear-end collision and start developing the neck pain, headaches and dizziness that are symptoms of whiplash? You see a doctor, of course. But there's not much a doctor can do for whiplash except prescribe special exercises and recommend over-the-counter pain relievers. There's no cure for whiplash -- except time. Over a period that can range from days to months, the symptoms simply go away, but you mostly just have to wait it out.
So the best way to deal with whiplash is not to get it in the first place. That's easier said than done, of course. There's not much you can do about that absent-minded driver who bumps you from behind, but automakers have stepped in to give you a hand. They've begun designing devices that will protect you from whiplash the way seatbelts and shoulder harnesses protect you from getting thrown through your car's front windshield. But to understand how these devices work, we'll first have to understand exactly what whiplash is.