I had to be sent to a physiotherapist to correct the issues caused by toe-walking as a child. My calf muscles had shortened and stiffened to the point where I was not able to participate in physical education without severe pain.
As an adult, I suffered from severe back pain until a physiotherapist explained the anterior pelvic tilt and helped me correct the years worth of compounded issues that stemmed from it.
It's a very real thing.