The Roman chair is designed to isolate and strengthen the back extensor (low back) muscles. The device places the person in a prone (face down) position. The legs are out straight. The spine is straight.
The chair keeps the pelvis and hips in correct alignment. The person starts by bending forward (at the waist). Then the upper back is extended (comfortably) as far as possible.
Some people can hyperextend (extend past a neutral position). And some Roman chairs are designed to provide a variable (rather than fixed) angle. Changing the angle increases the resistance to lumbar muscle activity.
Remember that every exercise program has some risk involved. With back strengthening exercise, musculoskeletal injury is possible. And back exercises performed under load can cause fracture or disc herniation. The risk is small but must be considered.
With the Roman chair in particular, great care must be used to avoid back injury. If you are new to the Roman chair exercise, consult a fitness professional when setting up your program.
Anyone with heart disease or heart health issues must seek medical advice before starting a new exercise program of any kind. There is a risk of heart attack or stroke with strenuous exercise for some people.