Some G-force reading

Just came across this interesting article. (Summary here.)

“As the researchers point out, an average person could momentarily experience eight to ten Gs by plopping down onto the couch to watch Top Gun.”

"What we should be concerned about is not G forces, but the effects of rapid head acceleration -- the rotational force on the brain that occurs as the body quickly changes directions," said co-author David F. Meaney, PhD, of Penn's Department of Bioengineering, "And, when we predict head accelerations in roller coasters -- the sudden twists and turns -- we find that they are well within established safety margins. It does not appear that roller coasters produce high enough forces to mechanically deform and injure the brain."

Note that biking with Chuckette produces about zilch in the way of rotational acceleration. Almost everything is vertical, from the bumps.

"The amount of rotational acceleration known to create injury in the white matter of the brain are roughly 18 times higher than the maximum accelerations calculated on the roller coasters,"

(Here is some roller coaster data recorded and graphed by the folks who made my accelerometer. They range from 2 to 4 Gs, but keep in mind that far from being instantaneous – like the 1/20th of a second, 3-G pulls from the bike trailer on a gravel road – these G forces are experienced for longer periods, even seconds, with no ill effects to riders.)

“Even for a conservative worst-case scenario, we found that the highest estimated peak head accelerations induced by roller coasters were far below conventional levels that are predicted for head injuries. Accordingly, our findings do not support the contention that current roller coaster rides produce high enough forces to mechanically deform and injure the brain.”

Roller coasters produce sustained G forces far in excess of what I’ve measured in the bike trailer and other experiments on Chuckette, and since these G-forces are less than 1/20th of a second in duration, they’re far less likely to produce any injury. Of course, no one’s going to put an infant on a roller coaster, but the principal here is what’s important. Leaving aside whiplash (which would injure the neck itself and possibly increase the acceleration of the head, upping the Gs), what I’m interested in here is the amount of G-force necessary to harm a brain.

Looks to me like the answer is likely, “a lot more than you’ll get with Chuckette in a bike trailer.”

 

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