Are you finding that your lats are lacking a little in the symmetry department? In other words, is one side more developed than the other?
Training bilaterally, as in with a fixed barbell or long bar attachment, can have the effect of allowing the stronger side of your body do slightly more work than the weaker one, creating a visual imbalance in your musculature.
Unilateral training (training each side independently) can solve this problem, creating optimal symmetry, and the one-arm lat pulldown is a great exercise for attacking this issue.
Tools
Lat pulldown machine
D-handle attachment
Execution
Attach a D-handle and position yourself as you would for a regular lat pulldown.
Reach up and grasp the handle with a neutral grip (palm facing in), with your torso fully erect, arm fully extended and chest out. (You may need to stand up first to pull the handle to you, then sit down on the seat.)
With your working arm fully extended, lean back 10–15 degrees and look straight forward.
Drop your shoulder by depressing your clavicles, and avoid pinching or shrugging your neck.
Squeeze your shoulder blades together, take a deep breath and pull the handle to your upper chest, focusing on the lats and pulling your elbow back and down.
Pause, then slowly release the bar back to the start.
Tips
Initiate the pull with slow, even force from the lats; jerking will cause your lower back and biceps to initiate the movement.
For variation and to hit the muscles from a slightly different angle, change your grip so your palm faces forward or backward.
To increase your lat involvement and range of motion, lean back as you pull through the movement.
To focus on the middle of your upper back (rhomboids, traps and lats), lean farther back and start your pull with your torso at a 45-degree angle.
For increased rear delt activation, flare your elbow out to the side, keeping it high throughout.
