Measuring Elbow Stiffness at Two Muscle Contraction Levels

The elbow joint is critical for positioning the hand to carry out activities of daily living. Deficits in elbow joint range of motion, torque production capabilities, or alterations in elbow joint stiffness affect the ability to successfully carry out feeding, grooming, and other essential activities [1]. Thus quantifying elbow joint stiffness is desirable. Quantifying elbow joint stiffness could help diagnose, monitor and rehabilitate elbow impairments if its relationship to them is known. Ultimately, accurate measurements of joint stiffness can also impact the design of artificial limbs and human motor system control and simulation. The long-term research goal is to quantify how elbow stiffness changes with elbow joint flexion angles, movement speeds, muscle contraction, and injury or disease. The immediate goal was to validate that a recently-modified Stiffness Tester measures elbow stiffness values within the range of those previously reported. The expectation was that muscle contraction level and joint position would influence the elbow stiffness values.