Bend over at the waist and grab a barbell with your hands placed shoulder width apart. Keep a slight bend in the knees. Lift the bar with your arms straight. Keep your upper body at a 45-degree angle to the floor and arch your back.
Moving just your arms row the barbell into your stomach. Hold this position and squeeze your back muscles for a second to maximize the peak contraction. Slowly lower the bar until your arms are straight, but do not let the barbell touch the floor in between each rep. Keep the tension on the muscles. Repeat.
Tips - For variety you can use an underhand grip (i.e. palms of the hands facing forward) this will work the lower lats more. You can also do this exercise with dumbbells or a low cable pulley.
Source: www.leehayward.com
