This exercise is used to build strength in the lower back and hamstrings. It will also provide a good stretch in the hamstrings at the bottom position.
Grab a bar with a double overhand grip; this is with your palms facing down. You should be holding the bar at thigh level with a tight core and a slight bend in your knees. Now, bend at your hips while keeping your back straight. You should push your hips back as you do this so that the barbell goes over top of your feet. Continue this movement until you feel a full stretch in the back of your legs. Next, bring the bar back up by pushing your hips forward and pulling the bar up. Complete the movement by locking your hips forward. Repeat this movement until you have completed your set.
You can use lifting straps if your grip fails and your legs still feel strong.
Keep your back straight the entire time. If your back rounds during the movement it could cause injury. This movement puts a lot of stress on your body; make sure you stick to proper form and weights that you can control.