Fig. 3.

This schematic demonstrates the relationship between moment arm and muscle fiber length and the consequences for a muscle's operating range. Increasing the moment arm increases the amount of stretch imposed on the muscle, thereby increasing its operating range for a given amount of angular rotation (compare elongated red lines estimating operating range in A and B with those in C and D). Increasing the muscle fiber length increases the number of sarcomeres to take up the imposed stretch, decreasing the operating range (compare shortened red lines estimating operating range in B and D with those in A and C).