Objective
The purpose of this study was to analyze the relationship between isokinetic measurement and electromyographic method in muscle power measurement of lumbar muscles. Method: The subjects were 23 chronic lower back pain patients and 17 normal adult. Isokinetic lumbar extensor strength test was performed at specific speeds (120^o/sec, 180^o/sec) with Cybex 770 and automatic turn/amplitude analysis of electromyogram (EMG) was performed with Viking EMG system. Results: The relationship between the parameters of isokinetic test and turn/sec of EMG study was not significantly correlated. The relationship between the para-meters of isokinetic test and amplitude of EMG study was significantly correlated. The relationship between the parameters of isokinetic test and ratio of turns to mean amplitude of EMG was not correlated significantly. The mean amplitude in 120^o/sec speed test and the ratio of turns to mean amplitude in 120^o/sec and 180^o/sec speed test were significantly lower in chronic lower back pain patients than that of normal controls. Conclusion: Turn/amplitude analysis of EMG method if performed with isometric or isokinetic muscle test will be clinically useful in muscle power measurement of lumbar muscles. (J Korean Acad Rehab Med 2002; 26: 759-763)