what makes one injury prone?

I know there is a vitamin or hormone deficiency that makes you prone to injury, but I don't remember what it is.

I seem to get hurt alot from doing nothing, pulled a groin muscle on the stepper, and hurt my shoulder walking the dog.

It's not like me, Years ago I did karate and weight lifting and not get hurt.
So, I am wondering if it is an age thing, or maybe I am deficient in something.

Thanks, mg Tweet