The reverse-grip barbell row builds strength in the back, shoulders, arms, and core. Using a reverse grip places more emphasis on the upper-back muscles.
Stand with feet shoulder-width apart. Grab barbell with an underhand grip just wider than shoulder-width apart. Let the bar hang straight down from your shoulders. Keeping your lower back naturally arched and shoulders back, bend at your hips and knees, and lower your torso until it is almost parallel to the floor.
Without moving your torso, pull the bar to your upper abs. Keep elbows tight to sides and squeeze shoulder blades together. Pause, then slowly lower the bar back to the starting position.
Be sure to finish the movement by pulling the barbell all the way to upper abs and pausing.
At the top of the row do not let your shoulders slouch. Be sure to bring your shoulder blades together.