Abstract
Force, velocity, and displacement properties of a muscle are determined in large part by its architectural design. The relative effect of muscle architecture on these physiological variables was studied by determining muscle weight, fiber length, average sarcomere length, and approximate angle of pinnation for 24 cat hind limb muscles. Muscle lengths ranged from 28.3 to 144 mm, whereas fiber lengths ranged from 8.4 to 105.5 mm. Generally, fiber to muscle length ratios were similar throughout a muscle. Estimated angles of pinnation of muscle fibers varied from 0 to 21ยฐ with most having an angle of less than 10ยฐ. The crossโsectional area of the knee extensors was similar to the knee flexors (16.43 vs. 16.83 cm^2^) whereas the crossโsectional area of the ankle extensors was more than six times greater than the ankle flexors (18.59 vs. 2.83 cm^2^). There was a 6.7โfold difference in the maximal force between muscles, when normalized to a constant weight, that could be attributed to architectural features. Rations of wet weight to predicted maximal tetanic tension for each muscle and group were calculated to compare the relative priority of muscle force versus muscle lengthโvelocity for a given mass of muscle. These ratios varied from 0.4 to 4.84. The ratios suggest that velocity and/or displacement is a priority for the hamstrings, whereas force is a priority for the quadriceps and lower leg muscles. As much as a 12.6โfold difference in maximal velocity between muscles can be attributed to differences in fiber lengths. This can be compared to approximately a 2.5โfold difference in maximal velocity reported to occur as a result of biochemical (intrinsic) differences.