If you could choose only one ergonomic feature in a chair, lumbar support should be it. This single element does more for spinal health during prolonged sitting than any other adjustment or design feature. Yet lumbar support is also one of the most misunderstood aspects of ergonomic seating—many people either don't use it correctly, choose chairs with inadequate support, or don't understand why it matters. This comprehensive guide explains the science behind lumbar support, the different types available, and how to optimise this critical feature for your body.
Understanding Your Lumbar Spine
The lumbar region consists of the five lowest vertebrae of your spine (L1 through L5), located in your lower back between your ribcage and pelvis. This section bears more weight than any other part of your spine—when you're sitting, the lumbar spine supports your entire upper body. The lumbar vertebrae are the largest in the spine precisely because of this load-bearing responsibility.
Critically, the healthy lumbar spine has a natural inward curve called lordosis. This isn't just aesthetic—the curve is biomechanically essential. It positions the vertebrae and discs optimally for weight distribution, maintains the proper spacing between vertebrae, and allows the spine to absorb shock and transmit forces efficiently.
What Happens When You Sit Without Support
When you sit on a flat surface without back support, your pelvis naturally rotates backward—a posture called posterior pelvic tilt. This rotation flattens or even reverses the lumbar curve, creating a C-shape through your lower and middle back. While briefly holding this position isn't harmful, sustaining it for hours creates problems.
In this flexed position, the front portions of your intervertebral discs are compressed while the back portions are stretched. Over time, this uneven loading can cause disc bulging, herniation, or degeneration. The ligaments along the back of your spine are held in constant tension. The muscles that normally maintain your posture become strained from working to support a mechanically disadvantaged position.
Studies show that sitting without lumbar support increases intradiscal pressure by up to 40% compared to sitting with proper support. Over thousands of hours, this accumulated stress significantly increases the risk of disc problems and chronic pain.
Types of Lumbar Support Systems
Chair manufacturers have developed various approaches to lumbar support, each with distinct advantages and limitations.
Fixed Lumbar Support
The simplest approach: a built-in curve in the backrest designed to support the lumbar region. This is common in basic office chairs and some ergonomic models. The main limitation is that spines vary—a fixed curve that fits one person perfectly may be too high, too low, or too prominent for another. If the fixed support happens to match your anatomy, it works fine. If not, you're stuck with inadequate or even uncomfortable support.
Height-Adjustable Lumbar
This system allows you to move the lumbar support up or down to align with your specific spine curvature. Since lumbar curve position varies between individuals—and even shifts slightly with different sitting postures—height adjustment is valuable. Mechanisms vary: some use a sliding pad, others move an internal support via a lever or knob, and some allow the entire backrest to shift.
Depth-Adjustable Lumbar
Beyond position, the amount of support matters. Depth adjustment controls how far the lumbar support protrudes into your lower back. People with more pronounced lumbar curves may need greater depth; those with flatter backs need less. Depth is typically controlled by a knob (often at the side or back of the chair) that tightens or loosens a tensioned support mechanism.
Combined Height and Depth Adjustment
Premium ergonomic chairs offer both adjustments, allowing complete customisation. This is the gold standard for accommodating different body types. Herman Miller's PostureFit and PostureFit SL systems, for example, provide independent control of both parameters, plus additional support for the sacral region.
Dynamic Lumbar Systems
Some advanced chairs feature lumbar support that moves with you as you recline or shift position. Rather than a fixed point of support, these systems maintain contact and appropriate pressure through a range of postures. This is particularly valuable for chairs designed to encourage movement and posture variation.
- Best: Combined height + depth adjustment, or dynamic systems
- Good: Height-adjustable with fixed but appropriate depth
- Acceptable: Depth-adjustable with fixed but appropriate height
- Minimal: Fixed support that happens to fit your body
- Avoid: No lumbar support or poorly positioned fixed support
How to Adjust Lumbar Support Correctly
Even the best lumbar support system is useless if incorrectly positioned. Follow this process to optimise your settings.
Step 1: Find Your Lumbar Curve
Stand naturally and place your hands on your hips, thumbs forward. Your lumbar curve is in the hollow just above where your thumbs rest—roughly at belt level, though this varies. Note this location; it's where you want the most prominent part of your lumbar support.
Step 2: Adjust Height First
Sit in your chair with your hips pushed back into the seat. Adjust the lumbar support height until the firmest point aligns with your natural lumbar curve. You should feel the support fitting into the hollow of your lower back, not pressing against your upper back or hips.
Step 3: Fine-Tune Depth
With height set, adjust depth. Start with moderate protrusion and increase gradually. The goal is gentle, consistent pressure that maintains your lumbar curve without feeling intrusive. Too little depth fails to support; too much pushes you away from the backrest or creates discomfort.
Step 4: Test and Refine
Sit normally for 20-30 minutes and assess comfort. Good lumbar support should feel like the chair is working with your spine—you shouldn't constantly notice it, but you should feel supported. If you find yourself slouching away from the backrest or feeling pressure points, readjust.
Positioning lumbar support too high (pressing against mid-back instead of lower back), setting depth too aggressively (creating discomfort that causes you to lean away), and setting-and-forgetting (your ideal position may change throughout the day or as your body changes). Lumbar support is worth periodic reassessment.
When Chair Lumbar Support Isn't Enough
Sometimes built-in lumbar support, even with adjustments, doesn't meet your needs. Several options can help.
External Lumbar Cushions
Aftermarket lumbar cushions attach to your chair via straps or simply sit against the backrest. Quality cushions use memory foam or firm foam cores and can significantly improve chairs with inadequate built-in support. They're also useful for adapting chairs in locations you don't control, like conference rooms or vehicles.
Choose cushions with adjustable straps so you can position them precisely. Avoid overly soft cushions that compress completely under pressure—they provide initial comfort but fail to maintain support over time.
Lumbar Rolls
Cylindrical lumbar rolls are a simple, portable option. They're easy to position and can be moved throughout the day. Some people prefer them for car seats or occasional-use chairs. Like cushions, look for rolls with firm enough construction to maintain their shape.
Consider Your Chair Choice
If you've tried multiple adjustment approaches and still lack adequate lumbar support, the chair may simply not suit your body. Lumbar support requirements vary significantly—some people need substantial support, while others are comfortable with less. Rather than fighting a poor fit with accessories, consider whether a different chair might be worth the investment.
Lumbar Support and Posture Habits
Even perfect lumbar support only works if you actually use it. Many people perch on the front edge of their seats, never contacting the backrest at all. Others slouch so far down that their lumbar support contacts their mid-back instead of their lower back.
Developing the habit of sitting with your hips pushed back into the chair is essential. When you sit down, consciously push your buttocks to the back of the seat before adjusting your position. This ensures proper contact with lumbar support and sets up your entire spine for better alignment.
That said, no single posture should be held rigidly for hours. Good ergonomic practice includes posture variation—occasionally reclining, shifting position, and taking movement breaks. Lumbar support helps ensure that your baseline seated posture is healthy, while movement prevents the problems of static loading.
For more guidance on chair adjustment, see our complete guide on how to adjust your ergonomic chair properly. And to understand why regular movement matters, read about the science of sitting, standing, and breaks.