Fig. 1.
Representative passive tension responses of mouse tibialis anterior fiber to step length increases. Five stretches were applied at a velocity of 1 fiber length (Lf/s), all from a resting sarcomere length (SL) of 2.1 μm and increasing in 0.2 μm/sarcomere increments, resulting in a mean sarcomere length of 3.1 μm after the final stretch. Detailed records for the final 2 stretches are shown. Tension was measured 2 min after each stretch as indicated by the arrows. Fibers were forced to slacken for 50 ms immediately after each tension measurement to indicate the location of zero on the tension record. Fibers were then returned to a sarcomere length of 2.1 μm and held there for 1.3 s before the next stretch.