Wow it's funny cause you can do heavy squats and heavy deadlifts, where me only doing the movement with an empty bar can be painful and expose me to lock-up in 0-3 days following it. And last time I tried hack-squat I just locked-up right there, barely been able to go home. For me leg press, is like pretty safe, I've hurt myself only once on it, but to be safe I start very slowly, I warm-up with only 2 plates on each side, then increase the weight slowly and make 15 slow reps each time up to my 2 last working sets. So far so good.

And I'm keeping the head straight, it was not hard at all to deprogram that habit to a new one.

Eric