BACKGROUND Lumbar stabilization exercise programs should normalize the aberrant movements patterns often observed in patients with low back pain. This study aimed to determine the effect of an 8-week lumbar stabilization program on EMG/kinematics measures of the aberrant movement patterns in such patients. A secondary goal was to assess the 8-week test-retest reliability of these measures. METHODS The patients followed an 8-week lumbar stabilization program while no intervention was carried out on the controls. Before and after this period, kinematics of the spine along with the EMG of paraspinal muscles were recorded during trunk maximal flexion-extension. ANOVAs tested the effect of the intervention in the patients, relative to the controls. Within the patients, correlation of the EMG/kinematics measures with the change in disability and pain following the intervention was investigated. FINDINGS A significant reduction in pain (Hedges's g effect size=2.31) and improvement in function (g=1.74) was reported in the patients. While EMG/kinematics measures disclosed impairments in the patients at baseline compared to the controls, no change was observed over the intervention. Nevertheless, the change of lumbar range of motion was positively correlated (r=0.42; P=0.015) with the change in disability. INTERPRETATION Although pain and disability decreased following the intervention, the EMG/kinematics measures did not change concomitantly suggesting that the patients learned to stiffen the lumbar spine during the treatment, and this technique was applied even if pain and disability unequivocally decreased after the treatment, which would not necessarily be beneficial to the patient.