I’m inclined to believe BJJ is a relatively safe sport despite the fact we all try to strangle each other or break each other’s leg.
Provided both players in a match/roll are skilled enough and know what they are doing, their chance of getting hurt, I bet, is low enough.
Even in a competition setting, I suppose you hardly see people getting hurt from actual submissions, including heel hooks. If injuries happen in a competition setting, such a match often occurs at a higher stake/level event.
I suppose it comes down to how much the players receiving a sub are inclined to tap in late situations and how much the players executing a sub are willing to hurt their opponents. Usually, that’s not how things go in a training context.
But people do get hurt and injured in BJJ, of course.
I don’t pretend to be a specialist who observed all sorts of BJJ injuries and collected data about it. So, take this as a grain of salt… but I feel that uncontrolled movements have more to do with injuries than, say, well-controlled submissions or techniques no matter how devastating these techniques can be (after all… you could die from getting strangled!).
I’m not kidding, but generally, I’m more on alert against white/blue belts, especially physically strong/big folks, than other black belts as far as sparring in a training session is concerned. The former group of people is more likely to be scared/tense and not to know what to do. As a consequence, they can make dangerous moves without meaning to do so.
On that note, here are some things you could do to stay safe…
1. Generally speaking, try to control your movements as much as possible. That can help you improve your skills AND avoid causing unnecessary injuries to yourself or to your training partners.
2. When you find yourself in a potentially sticky situation (i.e., basically, any situation where your knee, neck, or spine is in an unnatural/extremely uncomfortable position), try to slow things down or even ask your training partner to stop. That’s totally fine.
3. Tap early and tap clearly. It’s great to work on your defensive skills if that’s your intention, but there’s no point in trying hard not to tap when you don’t have clear ideas about how to escape from that situation. Tapping out is an essential part of your learning process, after all.
It’s so much better to stay away from severe injuries because you will be able to keep training on a regular basis.
Take care of yourself & your training partners!