The purpose of the present study is to evaluate the benefit of biofeedback training on the capacity of chronic low back pain patients to decrease their lumbar paraspinal muscles activity during trunk full flexion and its relationship with changes in clinical outcomes. To do so, twenty patients with nonspecific mechanical low back pain will be recruited and all participants will take part in four sessions of supervised biofeedback training, consisting of 5 blocks with at least 12 trunk flexion-extension tasks. It is hypothesized that participants will have improved neuromechanical parameters with the biofeedback training and that this improvement will be positively associated to changes in clinical outcomes. This study will also allow for generation of preliminary data, in order to plan for a larger randomized control trial.