Posterior Pelvic Tilt

Quick answer: Posterior pelvic tilt is when the top of the pelvis tips backward and the tailbone tucks under. It usually flattens the curve of the lower back and makes the buttocks look flatter. Everyone’s pelvis tilts back at times, such as when slouching in a chair; it becomes worth attention when it’s your default position in standing and sitting.

Maybe you’ve noticed your lower back looks flat, your pants sag at the back, or you tend to slump into chairs. Maybe you’ve been doing lots of “tuck your tailbone” and ab work and your posture feels stiffer rather than better. Here’s what posterior pelvic tilt is, and why it’s often overlooked.

What Is Posterior Pelvic Tilt?

Picture your pelvis as a bowl. With posterior pelvic tilt, the bowl tips backward: the front rises, the back drops, and the tailbone tucks under. Because the spine sits on the pelvis, the lower back usually loses some of its inward curve, often leading to a flat back. It’s the opposite of anterior pelvic tilt, where the pelvis tips forward.

Posterior Pelvic Tilt vs. Flat Back vs. Sway Back

• Posterior pelvic tilt describes the pelvis, tipped backward.
• Flat back describes the lower back, with too little curve. It often travels with posterior pelvic tilt, but not always.
• Sway back describes the hips sitting forward of the trunk. It can occur with the pelvis tipped backward, forward or level.

See our pelvic tilt entry for all four types of pelvic tilt.

How Can I Tell If I Have Posterior Pelvic Tilt?

1. Side-view photo. Have someone photograph you from the side while you stand normally. Does your lower back look flat, with your tailbone tucked under and your buttocks flatter than you’d expect?
2. Wall test. Stand with your heels a few inches from a wall and your buttocks and shoulder blades touching it. If your hand barely fits behind your lower back, your pelvis may be tucked.
3. Sitting check. Notice how you sit. Do you tend to roll back onto your tailbone rather than sitting on your sit bones?
4. Hip bone check. Place a finger on the bony point at the front of each hip and a thumb on your pubic bone. If the pubic bone sits noticeably further forward than the hip bones, your pelvis is likely tilted back.

What Causes Posterior Pelvic Tilt?

• Sitting habits. Long hours slumped back on the tailbone, especially in soft chairs and sofas, teach the pelvis to rest tucked under.
• Muscle balance. Tight hamstrings pulling down on the back of the pelvis, and lower-back and hip-flexor muscles that aren’t doing their share.
• Training cues. Lots of “tuck your tailbone” cues and abdominal work, without balancing work for the lower back and hips.
• Compensation. A rounded upper back (hunchback) or a forward head can be balanced by the pelvis tucking under.
• Medical causes. Less often, spinal conditions, previous spinal surgery, or neurological conditions that affect muscle tone. These need a doctor’s input.

What Are the Symptoms of Posterior Pelvic Tilt?

Some people have no symptoms. When there are symptoms, people commonly describe:

• Lower back stiffness or aching, especially with long periods of sitting
• Tight hamstrings that don’t loosen with stretching
• Difficulty sitting upright without slumping
• Hip or buttock discomfort
• Upper back and neck tension from compensating above

None of these proves posterior pelvic tilt is the cause. See a doctor if you have pain that travels down your leg, numbness, weakness, or changes in bladder or bowel control.

What the Research Shows

Posterior pelvic tilt is one of the few posture findings where the research leans toward it being worth attention:

Finding	What the research shows
How common it is	In 120 adults without back pain, the pelvis tipped back in only 6–7%; most tipped forward
Link with back pain	Across studies, people with back pain had flatter lower backs than people without, on average — a link worth taking seriously, though it doesn’t show which comes first
What exercise does	For chronic low back pain, exercise reduced pain by 15.2 points on a 100-point scale across 249 trials

So if your pelvis tends to tuck under and your lower back feels flat or achy, working on how your hips and lower back move is a sensible place to start.

How Do You Fix Posterior Pelvic Tilt?

If you’ve been told to “tuck your tailbone” or “flatten your back” in exercise classes, it can be surprising to hear that a tucked pelvis is part of the problem. You haven’t done anything wrong; that advice suits some postures and not others.

What tends to help is teaching the pelvis to find a more neutral position: improving how it rolls forward, balancing the hamstrings with the lower-back and hip muscles, and changing how you sit. How much your posture changes varies from person to person, and medical causes behave differently.

Exercises for Posterior Pelvic Tilt

Because posterior pelvic tilt and flat back share the same goal, these are the same four exercises we recommend for flat back. Move slowly and stop anything that causes pain. If you’ve had spinal surgery, check with your surgeon first.

1. Static Extension Position

Start on your hands and knees. Walk your hands forward 5 to 6 inches, then move your upper body forward so your shoulders are over your hands. Keeping your arms straight, let your back gently arch and your shoulder blades drop together, with your head relaxed. Breathe into your belly and hold for 60 to 90 seconds.

2. Sitting Knee Pillow Squeezes

Sit on the front edge of a sturdy chair with your feet flat, hip-width apart and pointing straight ahead. Roll your hips forward so your lower back gently arches, and keep your shoulders relaxed. Place a pillow or foam block between your knees. Squeeze it gently and release, keeping the arch in your lower back throughout. Do 3 sets of 20.

3. Cobra on Elbows

Lie face down with your legs straight, hip-width apart, and the tops of your feet on the floor. Prop yourself up on your forearms, elbows directly under your shoulders and forearms parallel. Keep your hips and thighs on the floor and let your lower back settle into a gentle arch. Relax your glutes and legs, draw your shoulder blades gently back and down, and breathe easily. Hold for 1 to 2 minutes, and ease off if you feel any pinching in your lower back.

4. Cats and Dogs

Start on your hands and knees, wrists under your shoulders and knees under your hips. Let your belly and shoulder blades sink toward the floor, arching your back. Breathing out, round your spine from your tailbone up through your upper back. Then let your back sink into the arch again as you breathe in. Repeat 10 times, spending a little longer in the arched position.

Choosing Your Next Step

There’s no single right path. It depends on how you like to work:

• You’d like to start on your own. The checks and exercises above are a sensible place to begin.
• You’d like someone to find what’s driving it. A free 30-minute consultation includes a postural assessment of how you stand, sit and move. We have clinics in Newton, Gloucester, Santa Monica, Beverly Grove and Middletown, RI.
• You’re not near a clinic. Virtual posture therapy brings the same assessment approach to you.

Frequently Asked Questions About Posterior Pelvic Tilt

What’s the difference between anterior and posterior pelvic tilt?

They’re opposites. In anterior pelvic tilt, the pelvis tips forward and the lower back usually arches more. In posterior pelvic tilt, it tips backward and the lower back usually flattens. See anterior pelvic tilt.

Does posterior pelvic tilt make your butt look flat?

It can. When the pelvis tucks under and the lower back flattens, the buttocks often look flatter or less rounded from the side. The muscles themselves may also be under-used in that position.

Is posterior pelvic tilt bad?

Not in itself. Everyone’s pelvis tilts back at times, and a slight tilt can be perfectly comfortable. It becomes worth addressing when it’s your default position, the pelvis can’t easily move out of it, or it comes with discomfort.

Can posterior pelvic tilt be corrected?

When it comes from habits and muscle balance, it often changes with consistent work and changes to how you sit. How much depends on the person and what’s driving it.

This article is general education, not medical advice. If you have leg pain, numbness or weakness, changes in bladder or bowel control, or have had spinal surgery, see a physician first. Posture therapy works alongside medical care, never instead of it.

Sources

• Herrington L. Assessment of the degree of pelvic tilt within a normal asymptomatic population. Manual Therapy 2011;16:646–648. 120 asymptomatic adults, palpation meter.
• Chun SW, Lim CY, Kim K, Hwang J, Chung SG. The relationships between low back pain and lumbar lordosis: a systematic review and meta-analysis. The Spine Journal, 2017. 13 studies, 796 patients and 927 controls.
• Hayden JA, Ellis J, Ogilvie R, Malmivaara A, van Tulder MW. Exercise therapy for chronic low back pain. Cochrane Database of Systematic Reviews, 2021. 249 trials, 24,486 participants.

Related reading: Pelvic Tilt, Uneven Hips and Lower-Back Posture: the complete guide.