Train your hamstrings without a glute-ham bench. This is a popular exercise and arguably the single best hamstring exercise ever invented.
How To Do It:
Kneel on the seat of a lat-pulldown machine, facing away from the stack. Secure your feet beneath the knee brace and grasp an empty barbell for support or have a partner stand by to help if needed. Beginning with your torso upright and your hips extended, slowly extend your knees to lower your body so your torso nears the floor. Go as far as you can without your lower back collapsing, then pull with your hamstrings to come back up. Use the bar or a partner’s hand to help you if needed.