avoid BACK PROBLEM DOING EXERCISES TO MAKE CORE STRONG

The difference between make your core strong to avoid back problems and have back problems to make your core strong".

​I was walking my dog this morning when I saw this guy walking in the sidewalk towards to the CrossFit gym, I couldn't resist and I took the pictures.

WHAT THE HELL DOES HIS TRAINER ASKED HIM TO DO?  DOES HE WANT TO MAKE HIS CORE STRONG?   

If yes, maybe all the kids should go to the school carrying the school bag in one side of the shoulders, as happened in the past. I though, it wasn't a good practice, if we want to avoid back problems. 

Poor guy, and DUMB TRAINER, before he makes his core strong, he is going to destroy his back.  
The said is, the client is spending money, he is getting tired,  and as benefit, he is going to have back problems.