As you might have gathered from reading some of the stuff on this site, I'm a big fan of repurposing exercises for targeting bodyparts other than the ones for which they're originally intended.
THAT is what this exercise is all about...
It's the top 1/4 of the Stiff-Legged Deadlift movement, done in the power rack but with a very important focus...instead of focusing on the hamstrings, you'll instead be pulling your back into a highly-contracted position THEN performing the movement.
This is going to put the majority of the tension on those back muscles so that they get worked with about double the weight (or more) that they normally would with a rowing exercise. And as you can imagine, this works VERY well.
The position at the shoulders resembles the top of a row (shoulders back) even though the arms stay straight.
I have to say, I just LOVE this one for building back thickness and for developing strength in the deep, stabilizing muscles of the back (upper to lower).
(I apologize for the frame on the pictures - the camera was a bit off kilter).
So first, you should be comfortable with the Stiff-Legged Deadlift exercise in general before doing this.
Set the pins in the power rack to just above knee height and load the bar. I'm using 425 lbs in this one (which is about my 3 RM for SLDL's). Use a weight you could do for at least 3 to 5 full reps on the full range stiff-legged deadlift when you try this for the first time.
Now here's the important part...once you've gripped on the bar, pull your chest towards the bar and pull your shoulders back, contracting all your back muscles HARD and lock them there.
You want to strive to keep this shoulders-back position through the entire movement as that's that real valuable part of this exercise.
Now lift the bar off the rails - squeeze it off, don't blast it off in one shot. You want to basically pull some bend into the bar then squeeze the bar off the rails.
Keep your shoulders back and tight. You'll feel the tension of the weight trying to pull your shoulders forward...do your absolute best to keep them back using those muscles of the back.
This exercise is also going to help your regular deadlift in that it'll help prevent your thoracic (upper) spine from curving forward. By building upper back strength, you can help minimize that curving and make heavy deadlifting safer. This is actually the reason I originally came up with this exercise...I was finding when I was doing deadlifts and hitting 550 lbs or more, my thoracic spine was rounding more than I'd liked.
Come up to vertical then lower the weight back down.
Set the bar fully on the rails. This is important because you want to reset your back position on every single rep, then go again.
The first time you do this one, you'll feel exactly how it's supposed to work. Pull your chest towards the bar, lock your shoulders back, then lift. Keep that lower back arched the whole way, too and keep your core tight. I also recommend holding your breath during the first part of the movement to keep your torso solid and stabilized.
This is a GREAT exercise for building thickness in the upper back. I'm actually kind of addicted to it, to be honest.
Heck, it's even a great exercise for increasing your bench press...after all, the thicker your back is, the shorter the range of motion the bar has to go in a bench press... ;). That plus, the back serves as the platform for the bench and a strong back that can keep the shoulders pinned tighter behind your back is going to do wonders for increasing your bench press numbers.