Bent-Over Barbell Row

Trains the Rhomboids and Middle Trapezius.

How to do it

Stand with your feet about hip-width apart and a loaded barbell over the middle of your feet.
Push your hips back and bend forward until your torso is somewhere between forty-five degrees and parallel to the floor. Keep a slight bend in your knees.
Take an overhand grip a little wider than your shoulders. Set your back flat and hold that shape for the whole set.
Let the bar hang at arm's length and allow your shoulder blades to travel forward slightly. This is the start position.
Pull the bar toward your lower ribs by driving your elbows back and out at roughly forty-five degrees from your body.
Finish the repetition by squeezing your shoulder blades together. This last part is the point of the exercise — the first part of the pull belongs to the lats and the rear deltoid, and the squeeze is where the rhomboids and middle trapezius do their work.
Lower the bar under control back to arm's length, letting the shoulder blades travel forward again before the next repetition.

Finishing the repetition when the elbow passes the torso. That is only half the movement. Without the last two or three inches where the shoulder blades draw together, the middle trapezius and rhomboids have barely been asked to do anything, and the set has trained the lats and biceps instead.
Standing up as the set goes on. The torso creeps toward upright, the bar path shortens and the load transfers to the upper traps. Pick a torso angle and hold it; if you cannot, the weight is too heavy.
Elbows tucked tight against the ribs. That is a lat row, which is a fine exercise and a different one. Elbows out at around forty-five degrees is what emphasises the upper-back muscles this movement is chosen for.
Jerking the weight up with the hips and lower back. If the bar only moves when the torso does, the arms and back are no longer doing the lifting. Take weight off and keep the torso still.