The lats are what give the back width. During a front double biceps pose, the lats outline the torso. From behind, they can make or break a top-place finisher before the first pose is struck. To fully engage the lats, research has confirmed that it’s tough to beat wide-grip pulldowns.
A lat’s function is arm adduction, either from above (for example, lat pulldowns) or in front (rows). Though wide-grip pulldowns are superior, some weightlifters avoid this movement because they’re able to move more weight with a close grip. This isn’t because the lats are working harder; in fact, it’s because the lats are sharing more of the load with other muscles, such as the biceps. In short, if they aren’t already, wide-grip pulldowns should be the foundation of your lat routine.