Back extension (Roman chair)
The 45° or horizontal back extension is a decent accessory for the glutes, hamstrings and back-muscle endurance, but it is a weak builder of lower-back strength: in two trials, 10–12 weeks of Roman chair training did not raise back-extension strength. For posterior-chain strength and size, hinge exercises such as the Romanian deadlift are the better base.
What the science says
- Builds lower-back strength Limited evidence
Mayer et al. (2003) trained 15 healthy adults on a 45° Roman chair for 12 weeks; isolated lumbar extension strength did not increase despite heavier training loads. Steele et al.'s 2015 review concluded that Roman chair and bench extensions are less effective for lumbar extensor adaptations than machines that lock the pelvis.
- Improves back-muscle endurance Moderate evidence
Shigaki et al. (2018) randomized 44 untrained young adults to 10 weeks of 45° Roman chair training: dynamic endurance rose by 61% with multiple sets and 26% with single sets, but maximal strength did not change.
- Works the glutes and hamstrings, especially at the top Moderate evidence
Andersen et al. (2021) found in 15 trained women that the Roman chair activated the gluteus maximus more than a seated back-extension machine and the biceps femoris more than both that machine and the Romanian deadlift; erector spinae activity was similar across all three. This is EMG, not measured growth.
How to do it
Muscles trained: erector spinae, glutes, hamstrings
- Set the pad just below the hip bones so you can hinge freely.
- Hinge at the hips with a neutral spine, lowering until you feel the hamstrings stretch.
- Rise until the body forms a straight line; don't hyperextend at the top.
- Move under control; don't swing.
How to apply it
Use it as an accessory for endurance or extra posterior-chain work after your main hinge, not as the main lower-back strength exercise.
Who should be careful
Low-risk for healthy adults when done with control and without hyperextending. People with back pain or a back condition should have a physician or physical therapist decide whether and how to use it.
Frequently asked questions
Does the back extension strengthen the lower back?
Not much: in two trials, 10–12 weeks of Roman chair training did not raise back-extension strength, though endurance improved.
What is it good for, then?
Back-muscle endurance and extra glute and hamstring work; it activated the glutes and hamstrings strongly in an EMG study.
What should I do instead for posterior-chain strength?
Make a hip hinge such as the Romanian or conventional deadlift your main exercise and use back extensions as an accessory.
Scientific references
- Effect of Roman chair exercise training on the development of lumbar extension strength
- Effects of Volume Training on Strength and Endurance of Back Muscles: A Randomized Controlled Trial
- Comparison of Muscle Activity in Three Single-Joint, Hip Extension Exercises in Resistance-Trained Women
- A review of the specificity of exercises designed for conditioning the lumbar extensors
More exercises
- Back squat Strong evidence
The barbell back squat reliably builds the quadriceps, glutes and adductors and is one of the best-studied lower-body exercises in training research.
- Front squat Moderate evidence
The front squat holds the bar on the front of the shoulders, which keeps the torso more upright and loads the knees less than the back squat while recruiting the thigh muscles about as much.
- Bulgarian split squat Moderate evidence
The Bulgarian (rear-foot-elevated) split squat trains one leg at a time and builds the quads and glutes with far less load on the bar than a back squat.
- Leg press Strong evidence
The leg press builds the quadriceps about as well as free-weight squats and also grows the glutes and adductor magnus, with no balance or spinal-loading limit.
- Hack squat (machine) Moderate evidence
The machine hack squat lets you squat deep on a fixed track with your back supported, which makes it easy to push the quads close to failure.
- Lunges Moderate evidence
Lunges (forward, reverse or walking) train the quads and glutes one leg at a time and highly activate the glutes.