What Happens To Your Body During A Crash

Your body does some pretty crazy stuff to keep you safe when things go sideways. Here's the blow-by-blow.


Selene Yeager |

It happens in the blink of an eye. One minute you’re humming along on the road or trail, and the next thing you know, you’re sliding across the tarmac or cartwheeling into a bed of rocks. Though the whole thing might play out in a matter of seconds, it can feel much longer, as your brain bends time and your body’s protective mechanisms spring into action.

“No crash ever looks as awesome in real life as it does in your mind because there’s so much going on in your head,” says Dr. Bruce Argyle, MD, a retired board-certified emergency physician and avid mountain biker.

This is what your body’s really up to when your ride hits a serious snag.

You Go All Deer-in-Headlights

In the split second, before you crash, you may experience what scientists call the “freeze” response – a survival mechanism produced by the periaqueductal gray (PAG) region of your brain. This reaction is similar to the fight-or-flight response, and can kick in during moments of extreme duress – like when you see a guard rail coming at you at 30mph.

“It gives you a second to assess your situation before making your next move,” says Argyle. “Ironically this response may actually lead to a crash when riders hold that freeze and analyse too long before getting their fingers off the brakes and responding in a way that may help them avoid a crash or minimise the impact.”

You Enter The Matrix

You know the scene: Time comes to a crawl and Neo goes all Plastic Man to dodge bullets. Crashes can feel a little like that because your neurons fire faster and your brain speeds up its sampling rate, says Argyle.

“Your brain needs more information quickly, so the link between your senses, neurologic processing, and higher awareness changes to send more frequent status updates to your conscious self,” he says. “The result can be a ridiculously detailed awareness of your surroundings, like the texture and color of the sagebrush leaves your body is rolling over as you part company with your bike.”

Stress Hormones Surge

Not even seconds into a crash, your brain’s amygdala is already sounding the alarm that bad stuff is going down. Your hypothalamus then signals your pituitary gland to release chemical messengers into your blood stream, and electrical signals head down your spinal cord. Both of these ping the adrenal glands, which sit atop your kidneys. Your body in turn, releases the stress hormones epinephrine and cortisol, setting off a cascade of physiological processes including an increase in blood pressure, surge in blood sugar, and dilation of the bronchioles in your lungs, so you have more energy and oxygen with which to take action.
crash
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Swelling Kicks In, And Increases After You Stop

Your body wastes no time in hustling your physiological first-aid crew to all your injured areas. The first responders are cytokines, which are molecules that facilitate cell communication as part of your immune response to trauma.

“These cytokines sensitize your nerves in the area of injury, and that process continues for three to four days, which is why injured areas often hurt more a couple of days after a crash,” he says. “Cytokines also call other immune cells into the area, which in turn recruit more immune cells, causing swelling and inflammation.” You’ll also see bruising in places where you’ve broken open the tiny blood vessels in your tissues.

You Ride It Off (Or Call It In)

Exercise is nature’s best pain reliever since it floods your system with so many feel-good chemicals. It’s for that reason that in many cases when a crash wasn’t too bad, it’s possible to “ride it off” and barely feel sore by the end of the ride.

When you’ve broken or otherwise more seriously damaged something, however, you tend to know it pretty much right away, says Argyle.

“There’s a deep sensation of, ‘That was bad,’ that you feel right away,” he says. Of course, there’s also telltale signs of serious injury, such as waves of nausea, lightheadedness, and sharp, awful pain in the injured area when you try to move. Listen to those warning signs. And, of course, if you’ve hit your head hard enough to damage your helmet or in any way give you pause, whip out your phone and get a ride to the closest medical centre.

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