We present methods to treat Low Back Pain (LBP) with electrical stimulation. The conventional method of treating LBP with electrical stimulation is based on mechanisms of reduction of pain. The method that we suggest uses electrical stimulation of trunk muscles at motor suprathreshold level synchronized with exercising of the trunk muscles. The hypothesis was that the combination of voluntary activity augmented with electrical stimulation would lead to higher levels of recovery of postural control and thereby, reduction of LBP. The electrical stimulation in this treatment was delivered with the lumbar belt with eight pairs of electrodes named Stimbelt. The outcome measures included: a Visual Analogue Scale (VAS), the Oswestry LBP disability questionnaire, the SF-12 health survey, and Manual Muscle Test (MMT). We specifically address the selection of the most appropriate statistical tests for the analysis of results. The analysis of the results of the clinical study indicates significant benefits of the addition of the Stimbelt to the conventional therapy.