-Increased pain with lumbar spine extension is consistent with lumbar spinal stenosis.
-Pain gets worse with spine extension. Spinal flexion reduces the pain.
Why?
“Spinal extension that increases lumbar lordosis decreases the cross-sectional area of the spinal canal, thereby compressing the spinal cord further. Walking downhill can cause this. Spinal flexion that decreases lordosis has the opposite effect and will usually improve the pain, as will sitting. ” ABFM critique.
Walking downhill vs. walking uphill: Which one causes flexion and which causes extension?
Follow the center of gravity.
An easy way to visualize which way the spine tends to go when walking up or downhill is to visualize where the center of gravity of an elderly person or child would need to be for them to avoid falling backward when going uphill or fall forward when going downhill.
When going uphill, the center of gravity must be ahead of the person to keep them from falling backward. If it’s perpendicular to the road with them standing up straight, the center of gravity will be behind them and they will fall backward. To put the center of gravity forward when going uphill, we flex our spines to do so.
Further Reading
Genevay S, Atlas SJ. Lumbar Spinal Stenosis. Best practice & research clinical rheumatology. 2010;24(2):253-265. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2841052/
Katz JN, Harris MB: Clinical practice: Lumbar spinal stenosis. N Engl J Med 2008;358(8):818-825.
Yuan PS, Albert TJ: Managing degenerative lumbar spinal stenosis. J Musculoskel Med 2009;26(6):222-231.