📖 Static demo — read-only snapshot
You’re browsing a static build of the Body IQ knowledge graph, so everything loads with no backend. A few things that need the live server are turned off here:
- Global search (sidebar) is disabled — it queries the API.
- The JSON API and the API “Try it” playgroundaren’t included.
- The data is a snapshot — it refreshes only when the demo is rebuilt, not live from the database.
Everything else — the body map, progression ladders, coverage heatmap, exercise finder, and all anatomy/exercise/source pages — works fully. The full app (live search + API + database) runs from the source on GitHub.
Lumbar Extension
Lumbar Intervertebral Joints • Lumbar Spine • sagittal plane
Backward bending of the lumbar spine. Arching the low back.
Axis: medial-lateral
Normal Range of Motion
True lumbar (not thoracolumbar) extension measured by double-inclinometer technique; the widely used norm is 25 degrees (AMA Guides). AAOS thoracolumbar extension is listed as 30 degrees. Tape-measure and single-inclinometer methods yield different units/values, so the 0-25 degree figure applies to the dual-inclinometer standard.
Source: AMA Guides (dual inclinometer); Norkin & White 2016
Muscles (5)
| Muscle | Role | Notes |
|---|---|---|
| Erector Spinae Group | Primary | Thoracic fibers: 50% of L4-L5 moment, 70-86% at upper lumbar levels |
| Multifidus | Primary | 20% of total extensor moment at L4-L5 |
| Quadratus Lumborum | Secondary | <10% of extensor moment [Phillips 2008] |
| Transversus Abdominis | Stabilizer | Via IAP |
| Diaphragm | Stabilizer | Via IAP |
Functional Tasks (1)
Exercises (16)
Sources
- Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation — Biomechanics of Lumbar Extension