Figure 1

Schematic structure of the three layers of organization inside a sarcomere: (a) global architecture with domineering parallel links; (b) structure of an elementary contractile unit shown in more detail in Fig. 2; (c) individual attached cross-bridge represented by a bistable element in series with a shear spring.Reuse & Permissions

Figure 2

Elementary contractile unit. (a) Energy of the bistable (power-stroke) element: HS model (thin line) and RHS model (thick line); (b) $N$ cross-bridges in hard device. In the HS model, ${\kappa }_0$, ${\kappa }_1$, ${\kappa }_f=\infty$ and $y=z$.Reuse & Permissions

Figure 3

Bifurcation diagram for the HS model placed in a soft device showing synchronized states (A and C) and a disordered state (B). Solid lines shows minima of the Gibbs free energy at $t=1$. The critical point is located at $\beta =4$.Reuse & Permissions

Figure 4

Recovery rates in hard and soft devices. Symbols: Postprocessing of experimental data; see 10. Open symbols, hard device; filled symbols, soft device. Dashed lines: HS model in hard (h) and soft (s) devices; parameters are taken from 2. Solid lines: RHS model in hard (h) and soft (s) devices obtained from stochastic simulations; parameters have been fit to experimental data: ${\lambda }_1=0.41$, ${\lambda }_0=1.21$, ${\lambda }_f=0.72$, $l=-0.08$, $N=112$, $\beta =52$ ($\kappa =2\mathrm{pN}/\mathrm{nm}$, $a=10\mathrm{nm}$, $\theta =277.13\mathrm{K}$), $z_0=4.2\mathrm{nm}/\mathrm{hs}$.Reuse & Permissions

Figure 5

Phase diagram for the RHS model in a hard device with $z$ selected to ensure that $⟨p⟩=1/2$ at each point ($\beta$, ${\lambda }_f$). In the shaded region, the function $f(p)$ is nonconvex which leads to coherent fluctuations. Outside this region, fluctuations are not synchronized. The cross indicates an almost critical configuration with realistic parameters (used in Fig. 4).Reuse & Permissions

Figure 6

Bifurcation diagram for the nonsymmetric RHS model with realistic parameters: (a) hard device with $z=0.37$; (b) soft device with $t=0.21$; this loading secures that $⟨p⟩=1/2$ for $\beta =52$. Parameters are as in Fig. 4. Inset (a) corresponds to $\beta =52$, inset (b) to $\beta =25$.Reuse & Permissions

Figure 7

(a) States attainable during quick recovery: solid line, $T_2$; dotted line, $L_2$; dashed line, $L_2^{\mathrm{qs}}$ corresponds to quasistationary states; dash-dotted line, $T_1$ and $L_1$. Symbols show experimental points for hard (open) and soft (filled) devices; see 10. In a hard device, the equilibrium $T_2$ curve coincides with the results of stochastic simulations. In a soft device, the equilibrium $L_2$ curve differs from the simulation results at 10 ms ($L_2^{\mathrm{qs}}$ curve). Averaged trajectories after abrupt loading at 1 ms: (b) in a hard device and (c) in a soft device. Curve (1): $\delta z=-1\mathrm{nm}/\mathrm{hs}$; curve (2): $\delta z=-5\mathrm{nm}/\mathrm{hs}$; curve (3): $t/t_0=0.9$; curve (4): $t/t_0=0.5$ with $t_0=0.21$. Other parameters are as in Fig. 4.Reuse & Permissions