Figure S3.

SL controlled isometric tension of a half-sarcomere. (A) Observed change in length of trabeculae per half-sarcomere (gray line) and corrected length of trabeculae to truly keep a half-sarcomere length isometric (pink line), which shows a decrease in trabecula length (i.e., motor position) toward the initial length of relaxed muscle. (B) Correction of the tension transient during the twitch due the change in SL (gray line in C). The observed tension (gray line) and the tension after correcting for the PE passive tension due to change of half-sarcomere length (red line) and also after additional correction for titin (passive) forces (pink line). (C) Change in half-sarcomere length (gray line) shows the effect of losing control of HS length that apparently should be constant (pink line). The tension of the trabecula length was fixed (black line in B) is shown for reference. The direction and color of the arrows signify changes in length and tension.