Recurrent symptoms of low back pain and its transition to a chronic state are associated with specific motor strategies used by people to avoid pain. The aim of the study was to determine the impact of chronic pain intensity on sit-to-stand (STS) strategy in chronic low back pain (CLBP) patients with herniated disks.
Vertical ground reaction forces (counter, peak, and postpeak rebound) and their respective times of occurrence were measured on 2 Kistler force plates. Thirty-two healthy persons served as a control group. People with CLBP were divided into 2 subgroups according to the reported pain intensity at rest as measured by the numeric pain rating scale: low pain and high pain.
Both CLBP subgroups achieved shorter time to counter force but longer time to postpeak rebound force. The time to peak force was extended in HP on the right side. HP presented lower peak force on the right and lower postpeak rebound force on the left side compared with controls.
Patients with CLBP were characterized by an individual, compensatory STS movement strategy with shorter preparation and longer stabilization times. Avoidance behavior in STS execution was presented in HP individuals only, indicating that intensity of chronic pain was a significant factor in decreasing ground reaction peak force and increasing time to peak force.