Physical therapy intervention: the treatment-based classification algorithm. Information from the history and examination is used to place chronic low back pain participants into one of two subgroups based on the pattern of signs and symptoms. Treatment is then based upon the participant’s subgroup classification. Participants’ classification is reassessed at each visit with appropriate adjustments to recommended exercises made. Participants are also classified according to the Fear Avoidance Belief Questionnaire (FABQ). PT participants who score ≥29 on the FABQ-W subscale receive The Back Book which provides brief cognitive behavioral education aimed at lowering fear avoidance. Physical therapists reinforce these points during treatment sessions and the participant’s exercise prescription is graded.