Fig. 1
Ex vivo experiment. a. Porcine tendons were clamped and cyclically loaded up to 300 N. A tapper device (Supplementary Fig. 2) delivered an impulsive 20 μm tap in the transverse direction at 40 ms intervals. Ultrasound radiofrequency data were collected at 14,100 frames per second from a single location along the tendon and used to track transverse tendon displacements. Scale bar, 2 mm. b An underdamped standing wave emerged in response to each tap (indicated by arrows) and was used to ascertain the natural frequency and corresponding shear wave speed. c Plotted are the mean (±1 s.d.) wave speeds versus the corresponding tendon stress for 10 porcine digital flexor tendons. The shaded region reflects the wave speed predictions using the wave propagation model (Eq. 2) with the following parameters: ρ = 1730 kg m−3; μ = 0.04–1.6 MPa; k’ = 0.9 (see Supplementary Methods, Supplementary Tables 1 and 2)
