Simulated effects of model parameter changes on force–velocity relationships for one-site and three-site models assumed to have linear cross-bridge elasticity. (A) One-site model where key parameter values, as indicated, are reduced by 50% compared with the control values (filled black symbols; same data as in Fig. 2 A). (B) Three-site model where key parameter values, as indicated by color coding in A, are reduced by 50% compared with the control values (filled black symbols; same data as in Fig. 2 A). (C) The data for one-site model in A replotted after normalization to isometric force and maximum unloaded shortening velocity. Experimental data (purple; from Månsson et al., 1989) are included for reference. (D) Data for the three-site model in B are replotted after normalization to isometric force and maximum unloaded shortening velocity. Experimental data (purple; from Månsson et al., 1989) are included for reference.