Abstract: Objective: To run functional test on the core stability of patients with chronic low back pain and observe the change in the core stability by comparing the results before and after rehabilitation training so as to provide the data reference for core stability function analysis and evaluation of chronic low back pain (CLBP) rehabilitation effect .Methods: Recruit and screen 31 CLBP patients as the experimental group(CLBP group), including 16 male vs 15 female. Meanwhile, recruit 29 health persons without back pain as the control group (Non group). Test and record theY Balance test of both groups. Then implement a 6-week rehab plan for the CLBP group, and repeat a Y Balance test after 6 weeks. The Y Balance test has 10 parameters including A/Limb、PM/Limb、PL/Limb、SUM,COMPOSITE in both sides. Analysis and compare the difference between two groups and the difference before and after the rehab plan.Result: 1. Compare with Non group, the CLBP group shows an obvious difference of the PM/Limb、PL/Limb(P<0.05), the results of CLBP group are much lower than the Non group. 2. When analysis the difference inside the group, we found there is only one parameter (the left PM/Limb) shows obvious difference between two sides(P>0.05); Meanwhile, the CLBP group shows obvious differences in three parameters(PM/Limb、PL/Limb、COMPOSITE) of two sides(P<0.01or P<0.05).3. After 6-week rehab plan, the Y balance test result shows obvious improvement of the CLBP group(P<0.05); 4. 6 weeks later, the difference between two sides of CLBP group of PM/Limb及COMPOSITE disappear,the difference of PL/Limb still exist, but the value reduces a lot, reduces from 3.52% to1.36%.Conclusion: 1. The dynamic core stability of CLBP patients decreased significantly, especially the posterior direction. The result shows obvious bilateral imbalance. 2. 6 weeks training increases the dynamic core stability effectively and improves bilateral imbalance.

Key words: chronic low back pain, core stability, Y balance test, pilate