Relationship between body mass and biomechanical properties of limb tendons in adult mammals.

We investigated the allometric relationship between the mechanical properties of various limb tendons and body mass. The elastic modulus (i.e., stiffness) and hysteresis (i.e., energy dissipation) of digital flexor, ankle extensor, and digital extensor tendons from 18 species of adult quadrupedal mammals ranging in body mass from 0.5 to 545 kg were determined by cyclic tensile testing in vitro. The results show that these elastic properties do not vary significantly among tendons from animals of different body mass, nor do they differ between the digital flexor and ankle extensor tendons (those situated to act as springs during locomotion) and the digital extensor tendons (those not likely to function as springs during locomotion). Consequently, the inherent capability of different limb tendons to store elastic energy, based on their material properties, is the same for large and small animals. The relationship between tendon elastic modulus (E; in GPa) and body mass (Mb; in kg) is described by the allometric equation E = 1.22Mb0.00. The hysteresis (H), as a percentage of total strain energy, is related to body mass as H = 8.89Mb-0.03.