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Abstrato

Does a History of Non Specific Low Back Pain Influence Electromyographic Activity of the Erector Spinae Muscle Group during Functional Movements?

Nicolas Mazis

Purpose: The present study aimed to identify potential muscular activity differences of the erector spinae muscle group between NSLBP individuals and healthy controls.

Methods: 37 Queen Margaret University (QMU) students were recruited to serve as subjects. Based on LBP information obtained by the Nordic Questionnaire, they were assigned to one of the three experimental groups: subjects who had experienced NSLBP within the past 12 months (W12), subjects who had had NSLBP anytime in the past but not within the last 12 months (A12) and healthy individuals who had never had an episode of NSLBP (C). Subjects performed a trunk flexion-extension protocol and the amplitude of bilateral EMG signals was recorded during different movement phases.

Results: Significant differences were revealed on the EMG values during standing, flexion, full flexion, flexionrelaxation ration (FRR) as well as on the side-to-side differences of these variables between the three experimental groups (p<0.0005). The side-to-side EMG signal difference during extension, varied significantly between the three groups (p=0.002). The control group varied significantly from the back pain groups at the variables of full flexion, FRR and standing (p<0.05). In flexion the control group differed significantly only with group W12 (p<0.0001) however, both back pain groups exhibited a greater side-to-side imbalance during this movement (p<0.005). The discriminant analysis clearly differentiated the control from the back pain groups.

Conclusions: The findings of the present investigation indicate that NSLBP can result in an increased and asymmetric activity of the erector spinae muscle group. No significant differences were detected between the two NSLBP groups, challenging the certainty of the results of previous investigations which characterize as healthy subjects, individuals who were asymptomatic of LBP for 6-12 months. The EMG activity in full flexion and the FRR as well as the side-to-side difference of these variables can be used as a criterion of identification of NSLBP individuals from controls.