Kinematic and electromyographical analyses of the lumbar and thoracic spine during standardized tasks

The purpose of this thesis was to assess: the movement patterns of the thoracic spine, modulating effects of the lumbar spine on the thoracic spine, and the flexion-relaxation phenomenon (FRP) in varying postures. Participants performed flexion and twisting tasks where the lumbar spine posture was controlled and the range of thoracic movement was determined. Flexion in the lumbar spine tended to increase flexion in the thoracic spine in both seated and standing postures. Minimal effects were noted on thoracic twist range. Average FRP occurrence was similar in the lumbar and thoracic spine during maximum flexion and slumped sitting. Lumbar flexion was associated with increases in thoracic FRP. Generally, a modulating effect of lumbar spine movement on thoracic spine movement exists. Off-axis postures yielded inconsistent occurrences of FRP. Establishing the interacting nature of the lumbar and thoracic spine is important in further understanding the possible mechanisms behind pain and injury.