Biomechanical properties of low back myofascial tissue in younger adult ankylosing spondylitis patients and matched healthy control subjects.

•Limited studies exist in the area of human resting muscle tone and its effects.•The role of muscle properties in ankylosing spondylitis has not been studied.•Few studies relate BMI, age, disease duration with muscle biomechanical properties.•Disease duration alters low back elasticity and stiffness in ankylosing spondylitis.•Relations between linear elastic and viscoelastic properties not altered by disease.