Stop doing your lat pulldowns wrong!
This is something we see way too often in the gym, and it deserves some serious attention. The Lats are anchored to the posterior iliac crest, and insert on part of the scapula and just below the anterior head of the humerus. When the Lats shorten, these boney attachments will move towards one another if there is no antagonist muscle activation. What does this mean? WELL, if your abs do not resist the tension from the Lats and control the anterior rib cage, the pelvis will move into excessive anterior pelvic tilt (listen and watch video for this cue). THIS IS NO GOOD for the low back. We see this all too often with people racking up the weight when there not controlling their pelvis before the weight increase.
LEARN TO CONTROL your pelvis and core with the lat pulldown. Keep your ribs pulled down, engage your abs, and dissociate the bar movement from your pelvis. The easiest way to learn how to do this and improve at the lat pulldown is to perform eccentrics (slow negatives). Learning how to control the bar back up while keeping your core tight will decrease the likelihood of excessive anterior pelvic tilt. Your lower back will thank you!