FIGURE 1.

Representative force tracing for a (a) slow active shortening (0.15 Lo/s) and (b) fast active shortening (0.6 Lo/s) for the rFD (blue) and isometric reference (black) conditions. (a) passive stretch of the reference isometric condition from the 2.5 to 3.1 µm. (b) activation in both conditions. (c) active shortening from 3.1 to 2.5 µm in the force depression condition. (d) instantaneous stiffness test in both conditions. (e) Deactivation in both conditions. Noise represents changing of baths. The order of contraction was always performed in the following sequence: rFD (slow), ISO, rFD (fast), ISO