Barbell Rows: Chest vs. Stomach
You hinge from your hips, pull a barbell with your arms and squeeze together your shoulder blades. A barbell row seems simple enough, until you start to really examine the movement. How far you hinge and where you aim the bar can make all the difference in a proper barbell row.
Ultimately, you want to hinge your hips to 90 degrees, so your back is parallel to the floor. You hold the bar with an overhand grip hanging straight down from your shoulders over your mid-foot. The most efficient and effective motion is to then pull the bar up in a vertical line from the floor to your lower chest. But, as with most exercises, you sometimes have to make exceptions — for the barbell row, this means that sometimes you'll pull toward your navel.
Hip Angle Matters
A proper barbell row has you hinge forward from the hips so that your back is parallel to the floor. Rising up too high — to, say, 45 degrees — takes a lot of the exercise's emphasis away from your latissimus dorsi and traps and puts it into your hips and thighs.
The angle also matters because the 90-degree angle at the hips allows you to pull the bar more effectively to your lower chest. If you don't hinge enough, you're tempted to pull the bar to the belly button, which sometimes reduces the effectiveness of the row in training the back muscles.
Note that as you pull a heavy weight to your chest, your torso will rise slightly with the momentum of the lift. That's OK, but don't let it go much more than 15 degrees higher than parallel to the floor.
Other Complicating Factors
Exactly to where on your lower chest you pull the bar depends on your physique and your grip. People with shorter torsos have less choice as to where along the chest the bar will hit. An underhand grip is more likely to encourage the bar to come to a lower position on your chest than an overhand grip.
An Argument for Pulling to the Abdomen
As you hinge forward, you might find tight hamstrings prevent you from getting your back parallel to the floor. Putting a slight bend into your knees helps you find the right hinge angle without making your hammies cry out. However, you might still find it nearly impossible to hinge all the way to 90 degrees.
Also, recognize that a 90-degree hinge from the hips, especially when combined with rowing a heavy barbell, can put a lot of pressure on the low back and just be unsustainable for many people.
Hinging forward also often manifests in a rounded back, which can cause pain, lead to disc herniation and diminish the effectiveness of the exercise. Engage your abs, visualize your collarbones spreading and reach the crown of your head forward to minimize rounding.
If, however, you find that bending your knees and visualizing a long spine just doesn't get you to the bent-over position that's ideal, hinge less aggressively and pull the barbell to your abdomen. Drawing to the navel keeps your arms pulling back and squeezing your shoulder blades together, rather than shrugging the shoulders and cheating the lift because you're so uncomfortable. Your back will still benefit from the rowing action.