Figure 7.

(a) Sarcomere lengths versus time for all six sarcomeres of a single myofibril, and (b) the corresponding force–length relationship for single sarcomeres based on the myofilament overlap theory and the actin and myosin filament lengths for rabbit skeletal muscle (open squares connected by solid lines), and the corresponding sarcomere forces achieved following myofibril stretching (filled squares). For the longest sarcomere following stretch (approx. 3.25 μm), the expected force is 58% lower than the maximal isometric force at the plateau of the force–length relationship, while the actual force was 44% above the maximal force. The vertical line connecting the open and filled squares represents the force enhancement for each single sarcomere. Note that the shortest sarcomere (following stretch) should be approximately twice as strong as the longest sarcomere based on myofilament overlap.