Researchers from New York Chiropractic College in Seneca Falls, New York have documented that chiropractic adjustments and spinal mobilization produce short-term inhibition of the human motor system.
To measure alpha motoneuron activity, researchers tested the tibial nerve Hoffmann reflex from the gastrocnemius muscle in 17 pain-free volunteers before and after spinal manipulation with thrust and mobilization without thrust. Both procedures inhibited alpha motoneuron activity immediately following intervention. Alpha motoneuron activity returned to pre-test levels within 30 seconds.
The study's authors concluded that their findings "substantiate the theory that manual spinal therapy procedures may lead to short-term inhibitory effects on the human motor system." These findings may explain why spinal manipulation reduces electromyographic activity in low-back pain sufferers, explain researchers. Dishman JD, Bulbulian R. Spine. 2000 (Oct 1); 25 (19): 2519-2524