I do an upper lower split -2 leg days and 2- upper. Body days. I love deadlifts but seem to have hit a wall . My current deadlift routine is some stretching followed by 2 sets of 15 @ 125 then 3 @ 315x8. Sometimes my lower back muscles get to tight to hit 3rd set . Should I warm up more or drop reps add sets and weight? Just looking for some insight?