Lumbar position sense with extreme lumbar angle

Area of Science:

• Biomechanics
• Human Movement Science
• Spinal Cord Injury Research

Background:

• Tasks involving flexed torso postures are linked to a high incidence of low back injuries.
• Altered low back motion sensing and control may contribute to these injuries.
• Previous research indicates increased lumbar spine position sense errors with torso flexion, but the effect of lumbar angle is less understood.

Purpose of the Study:

• To investigate how lumbar spine position sense errors change with torso flexion, considering different target lumbar angles.
• To determine the relationship between torso flexion, lumbar angle, and the accuracy of lumbar position reproduction.

Main Methods:

• Fifteen healthy volunteers participated in the study.
• A reposition sense protocol was employed to assess the ability to reproduce target lumbar angles.
• Subjects were tested at three torso flexion angles and three target lumbar angles (maximum, minimum, and mid-range).

Main Results:

• Reposition sense error increased by 69% with increased torso flexion for mid-range target lumbar curvatures.
• Increased torso flexion correlated with greater reposition sense errors, suggesting reduced lumbar spine sensation and control.
• Conversely, reposition errors were smaller at high torso flexion angles when targeting extreme lumbar curvatures.

Conclusions:

• Increased torso flexion appears to reduce lumbar spine sensation and control, potentially increasing injury risk, especially at mid-range lumbar angles.
• Proprioceptive feedback from structures like ligaments and facet joints may be crucial for sensing position at extreme lumbar angles, aiding in injury prevention.
• Sensory elements within muscles may enhance feedback at the limits of the range of motion, contributing to position awareness.