Fig. 5. Duty cycle and filament stiffness influence how work and ATP vary with respect to phase of activation (_Ca). Similar to Fig. 4, lines represent mean work (A), ATP (B) and efficiency (C) values; however error bars are not shown. Duty faction (_Ca) varied between 0.1 (blue), 0.2 (green) and 0.5 (black). Broken lines represent our standard mechanical parameters for the filaments and cross-bridges, listed in Fig. 2. Therefore, the mean data shown in Fig. 4 correspond to the grey broken lines shown here in Fig. 5. Solid lines represent a more compliant filament lattice, where both k_a and k_m were simultaneous scaled by a factor of 0.1 (k_xb did not change). As in Fig. 4, note the difference in ordinate scale between the left and right panels in A and C when =0.05 (left) versus 0.025 (right).