EdgeLine Steel Male Enhancement It's important when you do pull ups or lat pull downs to keep your thumb next to your index finger, not wrapped around the bar. If you simply place the thumb beside your index finger you will lessen the involvement of your arm muscles and focus on the primary back muscles. Although it may feel weird, it will assist you in targeting the correct muscles.
http://www.usafullreview.com/edgeline-steel-male-enhancement/