I was warned — thoroughly warned — and I didn’t listen. Look at me now.

I was told, don’t sit close to the television, you’ll ruin your eyes.

I was told, if you swallow chewing gum, it takes seven years to digest.

I was told, if you swallow watermelon seeds, a watermelon will grow in your stomach.

I was told, if you get a splinter and don’t remove it, it will enter your blood stream, go to your heart, and kill you.

I was told, don’t crack your knuckles, you’ll get arthritis.

So here I am, nearly blind from sitting too close to the TV (and many a computer monitor.)

Here I am, my stomach full of old gum that can’t get out because of the watermelons growing there.

Here I am, my bloodstream filled with childhood splinters, all working their way towards my heart.

Here I am, cramping up whenever I get near water, my system paying me back for all those 30 minutes I didn’t wait.

And here I am, my knuckles so racked with arthritis, I can’t change channels on the TV that is but a few feet away.

Just kidding.

My eyes are fine. Intrusive medical exams found no gum or watermelons. I have no blood-borne splinters. If I cramp, it’s from legumes. And my hands are arthritis free.

The only one of these childhood warnings that felt like it could be true is the last one, about cracking your knuckles. By cracked, I mean that intentionally produced popping sound made by stretching or bending a finger (or neck or back) joint.

In 1947, scientists had an idea of what caused the sound when a person bent a finger, stressing the joint. It had to do with the fluid — called synovial fluid — between the joints that cushions them. Stretching a finger (or other) joint stretches the sac of synovial fluid and creates a vacuum, causing a bubble to form. What couldn’t be determine is does the popping sound occur when the bubble is formed or when it pops.

In 1971, scientists were convinced it was when the bubble pops, but couldn’t prove it.

In 2015, fingers being cracked while being observed by MRI confirmed that a bubble is formed and that it pops. In 2018, it was found that the sound occurs when the bubble pops not when it is formed. It was also found that the reason a joint, once popped, can’t be popped again for about 20 minutes is that it takes that long for the bubble to fully dissipate and the fluid to return to its normal state.

There are no indications that cracking joints relates in any way to arthritis. In fact, as an experiment, a doctor named Donald Unger began to daily crack the knuckles of his left hand but not those of his right. He did this for fifty years. At the end of that time, there was no difference in the health of his two hands. So there.

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