Date of Award


Document Type


Degree Name

Master of Science (MS)


Biomedical Engineering

Research Advisor

William M. Mihalko, MD PhD


John L. Williams, PhD Audrey R. Zucker-Levin, PT, MBA, GCS, PhD


low back pain, motion analysis, tight hamstrings


The etiology of nonspecific low back pain is sparsely understood. To better understand the contributing factors to nonspecific low back pain, there are often common concurrent pathologies that are investigated to determine their functional relationship to low back pain. One such pathology, investigated further in this thesis, is tight hamstrings. Specifically, the effect of hamstring length on pelvic position during gait and activities of daily living under normal and altered spinal position were investigated as part of this study in a motion analysis lab.

First, a marker validation study was conducted to ensure the accuracy of sagittal spinal measures of lumbar lordosis, thoracic kyphosis, and sagittal vertical axis, which are calculated using skin markers. Lateral x-rays taken by the EOS bi-planar scanner were used to measure both clinical and marker measures. Sagittal spinal measures were also output by the built-in sterEOS software.

These measures were compared and found to be accurate within clinical requirements, despite inaccuracy of individual marker placement in identifying intended spinal anatomy. After validating the accuracy of spinal measures of interest for this study, kinematics of the pelvis and spine were analyzed during normal gait under two conditions: at a normal and altered spinal position. This revealed a unique pelvic compensation pattern in those with tight hamstrings to changes in lumbar lordosis. While other study participants exhibited varied pelvic responses to changes in lumbar lordosis, those with tight hamstrings responded with a -0.7° ± 1.6° decrease in pelvic tilt for every 1° of decreased lumbar lordosis (R2 = 0.94).

Finally, a similar kinematic analysis was conducted during stair ascent and descent. The results of this analysis, however, revealed a more random pelvic compensation pattern to changes in lumbar lordosis even among those with tight hamstrings. A kinematic and kinetic analysis of the angles, moments, and powers at the hip, knee, and ankle during stair ascent and descent also revealed no significant differences between those with and without tight hamstrings, with the exception of hip kinematics during swing phase of stair ascent (p = 0.047).