My first injury in Aikido was my poor poor ego. Having studied a little of a couple other arts, I thought I was pretty good. Then, my first Sensei greeted this new Aikido student with,
"So you want to learn Aikido? Please do a forward roll for me. OK...Not bad. Now do a backward roll for me. Again, not bad. Now please do them up and down the mat while we practice."
This continued for a couple weeks. Let me tell you.......My stomache and ego both suffered!!!
But, I found that after a while, my ego was something I could do with a lot less of. And when thrown, well....I did not suffer any serious injury. But my stomache still balks a bit when I do too many rolls. Old age is not fun!!!!
So, my ego was my first injury. And except for a couple minor bumps and bruises, that one can get playing Full-Contact-Golf, I have not had any real sserious injuries since I started Aikido