Open AccessShock attenuation in the human lumbar spine during walking and running
Author(s) -
Eric R. Castillo,
Daniel E. Lieberman
Publication year - 2018
Publication title -
journal of experimental biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.367
H-Index - 185
eISSN - 1477-9145
pISSN - 0022-0949
DOI - 10.1242/jeb.177949
Subject(s) - sagittal plane , supine position , lumbar , anatomy , kinematics , medicine , treadmill , coronal plane , physics , physical therapy , surgery , classical mechanics
During locomotion, each step generates a shock wave that travels through the body toward the head. Without mechanisms for attenuation, repeated shocks can lead to pathology. Shock attenuation (SA) in the lower limb has been well studied, but little is known about how posture affects SA in the spine. To test the hypothesis that lumbar lordosis (LL) contributes to SA, 27 adults (14 male, 13 female) walked and ran on a treadmill. Two lightweight, tri-axial accelerometers were affixed to the skin overlying T12/L1 and L5/S1. Sagittal plane accelerations were analyzed using power spectral density analysis, and lumbar SA was assessed within the impact-related frequency range. 3-D kinematics quantified dynamic and resting LL. To examine the effects of intervertebral discs on spinal SA, supine MRI scans were used to measure disc morphology. Results showed no associations between LL and SA during walking, but LL correlated with SA during running (p<0.01, R2=0.30) resulting in as much as 64% reduction in shock signal power among individuals with the highest LL. Patterns of lumbar spinal motion partially explain differences in SA: larger amplitudes of LL angular displacement and slower angular displacement velocity during running were associated with greater lumbar SA (p=0.008, R2=0.41). Intervertebral discs were associated with greater SA during running (p=0.02, R2=0.22), but after controlling for disc thickness, LL remained strongly associated with SA (p=0.001, R2=0.44). These findings support the hypothesis that LL plays an important role in attenuating impact shocks transmitted through the human spine during high-impact, dynamic activities such as running.