Home / Guides

45-Degree vs 90-Degree Back-Extension Bench

Shop for a back-extension bench and you will find two shapes sold under the same names. On a 45-degree bench your body sits on a diagonal, with your feet anchored low and behind you and your hips on a pad above them. On a vertical 90-degree Roman chair your legs are held level with the floor, and at the bottom of a rep your torso hangs straight down.

I got stronger on the 45. The program on this site and the app are both written for it. The program is not written for the vertical chair, so there is no conversion to look up. If a vertical chair is the only one you can reach, the next step is finding a 45.

Why the angle changes the exercise

How hard your back works depends on how far your upper body sits out past your hips, measured along the floor. On the vertical chair your body is level at the top of every rep, so the top is the hardest point. On the 45 your body stays on a diagonal at the top, where your upper body sits out only about 70 percent as far as it does when level (that is the cosine of 45 degrees). The hardest point on the 45 comes partway down, where your torso passes level with the floor.

The program starts in that easier top position. Stage 1 is 3 holds of 15 seconds at the top, with 60 seconds of rest. Stage 2 adds partial reps, starting at 3 sets of 3 through half the range. Stage 3 is full reps with body weight, and Stage 4 adds a plate at the chest, starting at 10 lb. The vertical chair has no easy position at the top to hold, so none of those numbers mean the same thing on it.

The 70 percent comes from the angle alone. Real forces also depend on your build, where the pad sits, and how you move.

How to tell them apart in a listing

Ignore the product title. Retailers call both machines a Roman chair, a hyperextension bench, or a back-extension bench, and some use all three names on one page. Find a side-view photo.

• On a 45-degree bench the hip pad sits on a diagonal post, and the ankle rollers are lower and behind it.
• On a 90-degree station your legs are held level, with the ankle rollers at about the height of the hip pad. At the bottom of a rep your torso hangs straight down.
• Adjustable models that claim both angles need a second look. The manual should show 45 degrees as a locked position with its own ankle setting. A pad that tilts on a frame built for 90 does not count.
• Owner photos are more reliable than product renders, which sometimes distort the angle.

Strong lifters use the vertical chair for hard high-rep sets, and that is a reasonable use of it. This program is not written for it at any stage, including the weighted one.

If your gym only has the vertical chair

Do not adapt the program to it. Ask the staff whether there is a 45 somewhere else in the building, because gyms label it under all the names above. After that, try another branch, a day pass at another gym, or a bench for home. The gym guide and the buying guide cover both routes.

Until you have a 45, Floor Foundations keeps you training. Each round is a prone hold, 6 bird-dogs, and 8 glute bridges. It lasts only until you have a bench. When your prone holds reach about 30 seconds a round across several sessions and your mornings are no worse than baseline, you are ready for Stage 1.

Once you have the right bench

Set the top of the hip pad at your hip crease so your pelvis can roll over it. The ankle rollers should hold you firmly without numbness or pressure pain. Check every pin before a set, and put the bench on a level floor.

Then start with the Stage 1 holds in the progression guide, even if you think you could do full reps today. The holds are where you learn the setup and find out what your back tolerates.

Common questions

Can I do this program on a 90-degree Roman chair?

No. The program is written for a 45-degree back-extension bench. On a 90-degree chair your body is level at the top of every rep, so the Stage 1 holds and the partial reps have no matching easy position, and none of the numbers in the program carry over.

Is a 45-degree back extension easier than a 90-degree one?

At the top, yes. On a 45 your upper body sits out about 70 percent as far past your hips as it does at the top of a 90, where each rep is hardest. Partway down on a 45, where your torso passes level with the floor, the demand peaks at about the same level.

The app