Your back is supposed to curve inward at the lower spine. A healthy lumbar spine has a natural inward curve of about 40 to 60 degrees. But if that curve looks or feels exaggerated, pushing your belly forward and your buttocks out, you likely have what’s called hyperlordosis, sometimes referred to as swayback. The most common cause is a pattern of muscle imbalances that develops over time from prolonged sitting, weak core muscles, or carrying extra weight around your midsection.
Why Some Inward Curve Is Normal
Your spine isn’t a straight column. It has three natural curves: a slight forward curve in your neck, a backward curve in your mid-back, and a forward curve in your lower back. These curves work together like a spring to absorb shock and distribute the load of your body weight. The inward curve at your lower back (the lumbar lordosis) is what lets you stand upright, walk, and bend without putting all the force on a single point in your spine.
The issue isn’t having an inward curve. It’s having too much of one. When the curve exceeds the normal range, your lower back compresses unevenly, your pelvis tilts forward, and your posture shifts in ways that can cause pain and stiffness over time.
The Muscle Imbalance Behind Most Cases
The most common reason for an excessive inward curve is a predictable pattern of tight and weak muscles known as lower crossed syndrome. If you sit for most of the day, this pattern probably sounds familiar: your hip flexors (the muscles at the front of your hips) and the muscles running along your lower spine get tight, while your abdominals and glutes get weak. The tight hip flexors pull the front of your pelvis downward, tilting it forward. Your weak abs can’t resist that pull, and your weak glutes can’t stabilize the pelvis from behind. The result is a pelvis that tips forward like a bowl spilling water out the front, dragging the lower spine into a deeper curve.
This isn’t just about sitting too much, though that’s a major contributor. Wearing high heels regularly shifts your center of gravity forward and forces your lower back to compensate with more curve. Sleeping on your stomach with no support under your hips does something similar over time. Any habit that keeps your hip flexors shortened and your glutes inactive reinforces the pattern.
Pregnancy and Extra Abdominal Weight
Carrying significant weight in front of your body pulls your center of gravity forward, and your lower spine curves deeper to compensate. This is why hyperlordosis is so common during pregnancy. Research tracking pregnant women found that the lumbar spine curve increased by roughly 2.7 degrees compared to non-pregnant controls, with the change becoming more pronounced in the third trimester as body weight increased. That may sound small, but it’s enough to cause noticeable lower back pain and postural changes.
The same mechanism applies to anyone carrying extra weight around their midsection. A larger belly shifts your center of mass forward, and your spine responds by arching more to keep you balanced over your feet. In pregnancy, the curve typically returns to normal after delivery. With abdominal obesity, it persists until the load changes or the supporting muscles get stronger.
Structural and Medical Causes
Not all excessive curvature comes from muscles and posture. In some cases, a structural problem in the spine itself is responsible.
Spondylolisthesis is one common example. This happens when one vertebra slips forward out of alignment and presses on the vertebra below it. That slip changes the geometry of the spine and can deepen the curve, often with accompanying back pain, stiffness, or nerve symptoms like tingling in the legs. It ranges from mild (low-grade, where the slip is small) to severe (high-grade, which is more likely to need surgical correction). Doctors diagnose it with X-rays, CT scans, or MRI.
In children, certain genetic conditions can affect spinal curvature. Achondroplasia, the most common form of short-limbed dwarfism, alters how bone develops and produces a steeply angled sacrum (the triangular bone at the base of the spine). This steep angle forces the lumbar spine to curve more aggressively to compensate. About 80% of adults with achondroplasia also have an abnormal angle at the junction between the mid-back and lower back, which contributes further to spinal imbalance.
Disc degeneration, previous spinal fractures, and neuromuscular conditions that weaken the trunk muscles can all deepen the lumbar curve as well.
What an Excessive Curve Feels Like
The most obvious sign is visual: your lower back has a pronounced arch, your belly pushes forward even if you’re not overweight, and your buttocks stick out. You might notice a gap between your lower back and the back of a chair that feels larger than normal.
Pain tends to show up as a dull ache across the lower back, especially after standing or walking for a long time. The compressed facet joints at the back of each vertebra bear more load than they should, which can cause localized tenderness. Over time, the uneven forces on your spinal discs can accelerate wear and contribute to nerve compression, leading to pain that radiates into the buttocks or legs. Stiffness when trying to straighten up after bending forward is common.
A Simple Way to Check at Home
Stand with your back against a flat wall. Your heels, calves, buttocks, and shoulder blades should all touch the wall. Now slide your hand behind your lower back, between your spine and the wall. If there’s just enough space for your flat hand, your curve is likely in the normal range. If you can fit a clenched fist or more, your lumbar curve is probably excessive. This isn’t a diagnosis, but it gives you a reliable sense of where you stand before seeing anyone about it.
How Doctors Measure It
When a more precise answer is needed, doctors use a standing X-ray and measure what’s called a Cobb angle. A radiologist draws lines along the top edge of the highest vertebra involved in the curve and the bottom edge of the lowest, then measures the angle between them. A lumbar Cobb angle beyond 60 degrees generally confirms hyperlordosis. This measurement also provides a baseline to track whether the curve is stable or worsening over time.
Exercises That Reduce the Curve
Because most cases of hyperlordosis are driven by tight hip flexors and weak glutes and abs, the fix targets those exact muscles. The goal is straightforward: stretch what’s tight, strengthen what’s weak, and retrain your pelvis into a more neutral position.
Pelvic Tilts
Lie on the floor with your knees bent and feet flat on the ground, hip-width apart. Place one hand under your lower back. Tighten your abs and glutes to press your lower back flat against your hand, tilting your pelvis backward. Hold for 10 seconds. Repeat up to 10 times. This teaches you what a neutral pelvis feels like and activates the muscles that maintain it.
Abdominal Drawing-In
Lie on your back with knees bent and feet flat. Tilt your pelvis slightly forward to flatten your back toward the floor, then settle into a neutral position. Take a deep breath, and as you exhale, draw your belly button toward your spine as if hollowing out your lower abdomen. Hold that contraction without tensing your ribs or holding your breath. Start with five repetitions per day lying down. As it becomes familiar, practice the same activation while sitting or standing, which is where it matters most for your posture throughout the day.
Hip Flexor Stretches
A basic kneeling lunge stretch targets the tight hip flexors directly. Kneel on one knee with your other foot flat on the floor in front of you, knee at 90 degrees. Shift your hips forward gently until you feel a stretch at the front of the kneeling hip. Keep your torso upright rather than leaning forward. Hold for 20 to 30 seconds on each side. Doing this daily, especially after long periods of sitting, helps release the pull that tips your pelvis forward.
Glute Bridges
Lie on your back with knees bent, feet flat, and arms at your sides. Squeeze your glutes and lift your hips toward the ceiling until your body forms a straight line from shoulders to knees. Hold at the top for a few seconds, then lower slowly. This directly strengthens the glutes that are supposed to stabilize the back of your pelvis and counteract the forward tilt.
Consistency matters more than intensity with these exercises. The muscle imbalance developed over months or years of habitual posture, and reversing it takes sustained effort, typically several weeks of daily practice before the curve and any associated pain begin to improve noticeably.