h-reflex attenuation after lumbosacral manipulation in patients with low back pain

Spinal manipulation is a manual technique commonly used for the treatment of low back pain. the physiologic mechanisms of the spinal manipulation are largely unknown. one basic physiologic response for spinal manipulation is an alteration in motoneuronal activity, as assessed by the hoffmann reflex (h-reflex) technique. the purpose of this study was to determine the effect of spinal manipulation on the amplitude and onset latency of h-reflex and on h/m amplitude ratio in patients with low back pain. fifty-eight patients with low back pain aged between 20-60 years, who had no exclusion criteria were included. tibial nerve h-reflex and m wave were recorded before and after lumbosacral spinal manipulation. lumbosacral manipulation significantly decreased the amplitude of the h-reflex and h/m amplitude ratio (p<0.05). it had no significant effect on h-reflex latency or m wave amplitude and latency (p>0.05). lumbosacral manipulation produces attenuation of alpha motoneuronal excitability. these findings support this theory that manual spinal therapy can lead to a reduction in muscle tone.