As with all of my answers this one has a caveat. The simple answer is no popping your knuckles or any joint is not bad for you. Here’s the caveat; anything to excess is not good.You should not be popping your knuckles, back or neck all the time. I’ve seen people who every 30 minutes or so will take their head and twist it “crackle”. This is probably not good, as every time you take your joints that far it puts stress on the joint capsule. Doing this too often can stretch out the ligaments and predispose you to injury. This is often seen in gymnasts. Too much flexibility can be a bad thing. Just like too little can be. Remember, there are three aspects to good exercising, strength, flexibility, and endurance. Keep them all in balance and life is good.
Popping your own joints can also cause injury, but more likely, you will just prolong your own recovery. Usually when a joint “locks up” movement will get it to release on it’s own. When it doesn’t, you can get pain. “Popping” your back on your own can relieve some of the pain temporarily but will often only “pop” the surrounding joints, leaving the “stuck” one “stuck.” A chiropractor isolates the “stuck” joint and corrects the issue. So while popping your own joints is not necessarily bad, you should seek a chiropractor for serious issues.
With the caveat out of the way, taking your joints through their full range of motion is good for them, and can actually reduce the chance of degeneration or arthritic changes.This doesn’t mean that if you pop your knuckles you won’t get arthritis, but the risk may be reduced. The old wives tale that popping your knuckles will give you arthritis is just that, a tale.
The popping is not perfectly understood the current thinking is that it is a cavitation. The pressure increases in the joint space causing the nitrogen or other gases to be “popped” from the liquid to gaseous form. It takes a refractory period before this can happen again. That’s why you can’t pop your knuckles immediately. For more information regarding what the pop does see my previous post on the topic.