Abstract: Objective To study the effect of isometric contraction on subaxial cervical instability with sympathetic nervous symptoms.Methods 41 subaxial cervical instability patients with sympathetic nervous symptoms were assigned to experimental group (n=21) and control group (n=20). Both groups received manipulation therapy. Experimental group received isometric contraction in addition. They were assessed with Visual Analogue Scale (VAS) and heart rate variability (HRV), including total power (TP), low frequency power (LF), high frequency power (HF), and LF/HF before and 3 weeks after treatment. Results The scores of VAS, LF and LF/HF decreased in both groups after treatment (P<0.05), which decreased more in the experiement group than in the control group (P<0.05). Conclusion Isometric contraction can release the sympathetic nervous symptoms post subaxial cervical instability.

Key words: subaxial cervical instability, sympathetic nervous symptoms, heart rate variability, isometric contraction