There are several variants of this exercise, depending on whether dumbbells or a barbell is used: Two arm barbell bent-over-row: This version uses both arms to lift a barbell from the floor to the stomach in a bent-forward position. The hands are kept pronated and the back straight. Two arm dumbbell bent-over-row: The barbell is replaced by two dumbbells, one for each hand. One arm dumbbell bent-over-row: This exercise is frequently performed with one knee and one hand on the same side of the body braced on a bench with the back straight and parallel to the ground, and the other hand holding a weight with the arm extended. The weight is lifted towards the hip until elbow bends past 90° and the humerus is in line with the back, then lowered to the original position. -Wiki-
