There used to be a Gixxer group on here and those guys were expert track junkies. Super skilled and a great source of information too. There is a trash talk thread on here somewhere and that is a fun read.
I have never crashed on a track but they are generally faster than street crashes. The low slides are usually more or less harmless but high sides are a bit more dangerous. I have mainly seen road rash, soft tissue damage to arms/legs, and occasionally a concussion. Breaks are less common but do happen, especially to the hands and feet/ankles. Good gear is a must! Many newbies get hurt trying to save the bike. Once a crash is inevitable, pull the ejection handle and get the F' out of there. It is important to separate from the bike, keep legs and arms high and tight and try to slide, not flip. Flipping breaks bones. You will hear track guys describe it as "sky, ground, sky, ground, sky, ground..." I experienced that on the road once and it is not a fun ride!
But fast crashes on a track are better than the slower ones on the street, at least for safety. If you are going fast enough to improve your riding and learn how to control a bike at speed, you'll eventually make a mistake. So it's hard to keep a dedicated track bike sparkling clean like you do your street baby. Track bikes are also setup different. To my way of thinking, a bike really takes damage when it flips or cartwheels. Frame sliders can catch in the sand or gravel pits turning a survivable mid-speed crash into a major repair. So some don't like sliders on the track. Obviously though if you don't run sliders you need all the other things like case savers. Anything else unnecessary is just more to fix. Mirrors, accessories, and anything heavy should go. I spend a week working on my bike stripping it and getting it ready for my track adventures.
Like anything prep pays big at the track. In the several I've done there weren't too many crashes, at least not big ones. I don't think anyone got the long ride (ambulance). My track buddy crashed his Ducati a lot. He wanted to be a racer and got his license but had some spectacular crashes getting it, Lol! He never got as much as a scratch though.
