Lie face down on a hyperextension bench, tucking your ankles securely under the footpads.
Adjust the upper pad if possible so your upper thighs lie flat across the wide pad, leaving enough room for you to bend at the waist without any restriction.
With your body straight, cross your arms in front of you (my preference) or behind your head. This will be your starting position.
Start bending forward slowly at the waist as far as you can while keeping your back flat. Inhale as you perform this movement. Keep moving forward until you feel a nice stretch on the hamstrings and you can no longer keep going without a rounding of the back.
Slowly raise your torso back to the initial position as you inhale.