The Lat Pulldown is an extremely popular exercise. No gym is complete without at least one pulldown machine. Yet, despite its popularity, the exercise lacks a standardized technique. It’s frequently performed with the bar pulled down behind the head, or, alternately,  by leaning back and pulling the bar to the chest. So the question arises: which technique is more effective for training the lats?
In a recent blog post, Mike Reinold, head athletic trainer and assistant director of medical services for the Boston Red Sox, compares the effectiveness of various Lat Pulldown techniques.
It turns out that the common method of pulling the bar to the chest while leaning slightly backward actually activates the traps more than the lats. If your goal is to target the traps, this is a great exercise; however, it’s insufficient for lat development.
According to Reinold, the most effective way to develop the lats is to pull the bar behind the head. If you want to activate only the lats, eliminate any backward lean and pull straight down. Unfortunately, however, this technique places elevated stress on the shoulders, which can cause discomfort or even injury.
So, what is the most effective technique to safely build lat strength? Reinold recommends pulling “through your head.” Instead of using a pulldown bar, perform the exercise with two separate handles. These enable you to pull your arms straight down in line with your head. The straight downward pull effectively activate the lats, while also keeping the shoulders in a safe position.
For a graphic demonstration of the different techniques, watch the following video:

Source:  mikereinold.com