alt Hacker Newsif you have the grip strength to hold that, you have solid core strength already.
And you are carrying in your hands, not balanced on your head-- which totally alters the stress on the spine.
So yes, cograts on your feat, that is a pretty cool level to hit, but it doesn't counter the basic advice of "grow into it" instead of "max from day one"
Also, you did this "once". If the accident rate is 1:100, doing it once without getting hurt is not very surprising.
Yes, I trained for it and did it maybe a couple of times in training and then at the event. If you want to do XXX kg every day, you need to make your max XXX+[20%+?].