The effects of spinal flexion exposure on lumbar muscle shear modulus and posture

Spinal flexion exposure (SFE) leads to alterations in neuromuscular and mechanical properties of the trunk. While several studies reported changes in intrinsic trunk stiffness following SFE, there is a lack of studies evaluating the effects on lumbar muscle shear modulus (SM). Therefore, the aim of our study was to investigate the effects of SFE on lumbar muscle SM and posture. Sixteen young volunteers were included in this clinical study. Passive lumbar muscle SM, lumbar lordosis, lumbar flexion range of motion and sitting height were measured prior to and following a 60-min SFE protocol. For SM, our results did not show a significant muscle × time interaction effect (p = 0.40). However, we found increased SM (from 6.75 to 15.43% - all p