well today i was squating and doing my usuall depth (legs parallel to ground). Well first let me mention im just fully recovered from a lower back muscle injury and finally starting to get back up in weight. Well anyways im under 315pnds going lil deeper then normal and felt real good so i decide to got up to 345 pounds. I felt really good on first 3 reps but on the forth soon as i broke 90 degrees my legs gave and i had to drop the bar. i walked away fine but **** that never happend before. What should i do i felt super strong and all of a sudden nothing. I wanna go back and try again next week but im nervous. any advice bros?