If you have a reverse hyper bench, use it. If not, you can perform them on a glute ham bench, jerk block, stacked plyo boxes, or similar. The forward swing at the bottom will be limited, so some of the effectiveness will be reduced, but it can still be valuable for lower back health.
 
Support the trunk and let the legs hang straight down. Keep the feet close to each other and swing the legs up as high as possible, keeping the abs and glutes tight to prevent excessive lumbar hyperextension. Let the legs swing back down and forward as far as your setup will allow and use the momentum to swing back up.
 
Purpose
The reverse hyper is a glute and lower back exercise that also helps decompress the lower back well and as a result can be helpful for tight backs or low-level back pain. It’s much better as a rehab/prehab exercise than a strength exercise.
 
Programming
The reverse hyper can be done light or unweighted as part of trunk prep in a warm-up, or with more volume and intensity at the end of a training session along with other trunk and accessory work. 3-5 sets of 10-30 reps depending on loading is a good prescription. Without a machine, resistance can be added with a light band or a dumbbell between the legs.