Balance Control Comparison between Subjects with and withoutNon-specific Low Back Pain*

Objective: To compare the balance ability between normal people and non-specific low back pain (nsLBP) patients and explore the relationship between balance ability and muscle function in nsLBP patients. Method: Ten nsLBP patients as nsLBP group and 10 age and gender-matched healthy control subjects as control group were investigated. Posturography on balance platform and surface electromyography (sEMG) were performed to assess all the subjects' function of equilibrium and muscle activities of erector spinea(ES), muhifidus(MF), abdominal external oblique (EO), hamstring (HS) and maximal gluteus (MG) bilaterally. Result: The nsLBP subjects had greater sway on anterior-posterior direction (Y-speed and Y-extension, P=0.05) on feet-together posture and bigger main axis (P=0.023) on nature standing with eyes closed when compared with controls. The iEMG ratios of right MG in nature standing (eyes closed)/ nature standing (eyes open) and feet-together (eyes open)/nature standing (eyes open) in control group were significant higher than that in nsLBP group (P=0.03 and P=0.013). Conclusion: Balance evaluation combined with sEMG measurement on trank and lower limb muscles provided some quantitative information about functional deficits such as pestural control and muscle activities in nsLBP patients. This relationship should be emphasized in prevention and rehabilitation of nsLBP.