How-to and differences between the front and rear lat pulldown.
As you see in the video I (Nancy) do the front pulldown. The first photo at the left shows the start position. Before I begin to pull the bar down i lean my torso back slightly, keeping my spine straight. As I begin the move I make sure to keep my spine steady and pull the bar down towards my chest. I pull down to below chin level and I keep the bar close to my chin.
The second photo shows the bottom position. Notice that my hands are in front of my shoulders. This keeps the shoulder joint out of extreme external rotation and there is less stress on the joint as a result. This position promotes more latissimus involvement and less emphasis on the Teres Major.
The third photo shows Bud in the start position for the rear pulldown. As he begins the move he drops his chin forward which will allow him to pull the bar behind his head. He keeps his torso upright for the duration of the exercise.
The final photo shows Bud in the bottom position. Notice that Bud's hands are behind his shoulders here. This position promotes external rotation of the shoulder and may have adverse effects on the joint over time. It does, however, emphasise Teres Major involvement.
Understanding the anatomy of the back can help one further their training.