This exercise is a great way to strengthen your lats and upperback. Begin by putting the bar across the safety pins in a power rack at about waist height. While lying underneath and keeping your torso straight, row your chest/upper abs to the bar. Make sure your torso does not sag. A wide variety of grips can be used. This is also a great way to assess core strength in an individual. If they cannot maintain their torso, it's time to start the ab/low back work.

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Jim Wendler