Figure A2.

Left: phase plane; the nullclines ${\overline{f}}^r$ and ${\overline{f}}^{\varphi }$ (dashed lines) are functions of ϕ and $\overline{t}$ and guide all the solution trajectories (solid lines) to the equilibrium point from different starting points (•); Right: Active fiber tension T^act (Φ). Parameters: ${ϵ}_0=0.1{\mathrm{\text{ms}}}^{-1}$, ${ϵ}_{\infty }=1.0{\mathrm{\text{ms}}}^{-1}$, $\tilde{\Phi }=0.0\mathrm{\text{mV}}$, ξ = 0.5 mV⁻¹, k_T = 0.40 kPa and Φ_r = −80 mV. Electrical characteristics as in Figure A1.