The Flat Back Guy
Flat back · Roussouly Type 2

Built flat.
Living well with it.

A flat back changes how you sit, run and lift, and most advice is written for a different spine. I’m testing what works on my own back and sharing the research behind it.

Check your spine type Start the deep dives
Bruce’s bare back photographed from behind and to the side in a sunny garden, showing a straight spine with almost no curve
Real photo · my back. Almost no curve.

Which spine type are you?

The Roussouly classification sorts spines into four shapes by the slope of the sacrum, the bone at the base of the spine. Most people have never been told theirs. Only an X-ray can confirm it, but the shapes are often visible side-on.

Type 1

Low sacral slope. A long curve in the upper back and a short, low curve in the lower back.

Type 2

THIS IS ME

Low sacral slope. Flat lower back and flat upper back: the flat back.

Type 3

Medium sacral slope. A balanced S-curve: the shape most advice assumes.

Type 4

High sacral slope. A long, deep curve in the lower back.

Source: Roussouly et al., Spine, 2005. Curious about yours? Have an X-ray or MRI? Try the spine-type check: your scan never leaves your device.

Deep dives

The full story behind each series: the mechanics, the studies and what I’ve found on my own back.

Series · 9 cues

Low-impact running

My spine can’t be the spring, so my legs have to be. Nine cues, each with its reel and the study behind it.

Read the deep dive →
Series · in progress

Sitting with a flat back

Why sitting brings on sciatica within minutes, why sitting up straight is pure muscle effort, and the search for a chair that holds the pelvis for you.

Read the deep dive →
Coming next

Lifting and the gym

Training without heavy loads down the spine: the calf, hip and trunk work behind my running comeback.

Research library

Every study I use, summarised in plain English, linked to the original, and honest about its limits.

Biomechanical responses of the lumbar spine and pelvis by Roussouly type Wang et al. · PLOS ONE · 2022 · Flat backs Computer models of Types 1–4: the straighter Type 1 and 2 models were less stable under load. A model, not people.
The evolution and function of human lumbar lordosis variability Castillo · Harvard PhD thesis · 2017 · Running Lower-back curve made no difference to shock absorption when walking, but a strong one when running.
Sitting with adjustable ischial and lumbar support Makhsous et al. · BMC Musculoskeletal Disorders · 2009 · Sitting Letting the back of the seat drop away cut lower-back muscle activity by 6–24%. 35 people; flat backs not tested.

Browse the full library →

My experiments

One flat back, tested honestly, setbacks included. Every result is n=1: a lead to explore, not proof.

Planned

KT tape as a posture reminder

Minutes until sciatica starts when sitting, with and without tape.

Ongoing

The café position

Leaning forward on my elbows: the one way I can sit for longer. Why I think it works.

Planned

The floating chair

A seat that frees the sit bones and the sciatic nerve path. The concept so far.

About

I’m Bruce. I have a flat back, a history of L5/S1 trouble and a lot of parkruns behind me. I’m not a clinician: I read the research, test it on myself and show my working.

Researchers and clinicians working on spinal shape: I’d love to help explain your work to the people it’s about. Message me on Instagram.