 Eligible participants are English-speaking adults 18 years of age or older. Additional criteria for asymptomatic healthy adults include no existing LBP and no LBP in the past year. Additional criteria for patient participants include existing LBP near the L5-S1 level with an average pain intensity score 210 in the past 24 hours numeric pain rating scale of 0-10, 0 being no pain, 10 being unbearable pain. Exclusion criteria for all participants include previous low back surgery, systemic joint disease e.g. rheumatoid arthritis, cancer of the lower quadrant, neurological disorders, allergic reaction to ultrasound gel, or inability to obtain testing positions prone lying. 