ABSTRACT
BACKGROUND AND PURPOSE: Pain is currently evaluated with "subjective" methods (eg, patient self-report). This study aimed to test whether fatigue indexes are able to accurately discriminate between subjects with and subjects without low back pain. SUBJECTS: Sixty subjects separated into 2 groups--a group with low back pain (n=30) and a group without low back pain (n=30)--participated in this study. METHODS: Electromyographic (EMG) and force data were obtained during a muscle fatigue test. The same test was repeated to monitor recovery. Linear regression analysis was used to obtain fatigue indexes. RESULTS: Subjects with pain produced significantly lower force values than those without pain. The use of fatigue indexes and force values permitted accurate classification in 89.5% of cases. DISCUSSION AND CONCLUSION: The results confirm that subjects with pain show early myoelectrical manifestations of muscle fatigue and that EMG can be a useful tool in the evaluation of low back pain.