Fig. 5.

(a) The deformations resulting from passive stretch and active contraction both enact the Poisson effect, where the longitudinal strain (horizontal arrows) results in strain in the transverse plane (vertical arrows). As these deformations oppose each other, the result is a smaller resultant volumetric deformation, which yields low fluid pressurization. (b) Model transverse strains (x and y directions, as elongation occurs in the z direction) for three time points when stretched to optimal length, after initial ramp elongation, at the end of stress relaxation, and at maximum contraction. Passive elongation results in negative transverse strains, which is then counteracted by shortening due to active contraction.