The role of hind limb tendons in gibbon locomotion: springs or strings?

Abstract

SUMMARYTendon properties have an important effect on the mechanical behaviour of muscles, with compliant tendons allowing nearisometric muscle contraction and facilitating elastic energy storage and recoil. Stiff tendons, in contrast, facilitate rapid force transfer and precise positional control. In humans, the long Achilles tendon contributes to the mechanical efficiency of running via elastic energy storage and recovery, and its presence has been linked to the evolution of habitual bipedalism. Gibbons also possess relatively long hind limb tendons; however, their role is as yet unknown. Based on their large dimensions, and inferring from the situation in humans, we hypothesize that the tendons in the gibbon hind limb will facilitate elastic energy storage and recoil during hind-limb-powered locomotion. To investigate this, we determined the material properties of the gibbon Achilles and patellar tendon in vitro and linked this with available kinematic and kinetic data to evaluate their role in leaping and bipedalism. Tensile tests were conducted on tendon samples using a material testing machine and the load-displacement data were used to calculate stiffness, Young's modulus and hysteresis. In addition, the average stress-in-life and energy absorption capacity of both tendons were estimated. We found a functional difference between the gibbon Achilles and patellar tendon, with the Achilles tendon being more suitable for elastic energy storage and release. The patellar tendon, in contrast, has a relatively high hysteresis, making it less suitable to act as elastic spring. This suggests that the gibbon Achilles tendon might fulfil a similar function as in humans, contributing to reducing the locomotor cost of bipedalism by acting as elastic spring, while the high stiffness of the patellar tendon might favour fast force transfer upon recoil and, possibly, enhance leaping performance.

Development and sexual dimorphism of the sonic system in three deep-sea neobythitine fishes and comparisons between upper mid and lower continental slope

“…An important question is the selective advantage and function of long tendons in the nutritionally dilute lower-slope environment. Tendon function in movement has been examined mostly in leg muscles in a variety of tetrapods -frogs, turkeys, kangaroos, wallabies and primates including humans (Alexander, 2002;Biewener and Baudinette, 1995;Lichtwark and Barclay, 2010;Vereecke and Channon, 2013;Sawicki et al, 2015;Mayfield et al, 2016). Leg movement generally involves muscle contractions over a range of 0.2-11 Hz (Alexander, 2002), which would result in a volume velocity too low to produce audible sound.…”

The gibbon's Achilles tendon revisited: consequences for the evolution of the great apes?

“…Moreover, the safety factor of the Achilles tendon (i.e. tendon strength over tendon loading) appears, together with that of the patella tendon, to be the lowest of all the hindlimb muscles in the gibbon [6,27,28]. A low (but safe) safety factor is required for functionally significant energy storage and recoil.…”

“…Furthermore, the ratio of the tendon length over the effective muscle fascicle length (i.e. accounting for pennation angle) is rather high for the triceps surae [6,27,28]). Such muscle-tendon morphology can be expected if the tendon needs to do the work.…”

“…stride ¼ left þ right step). To do so, the kinematic, dynamic, material property and anatomical data collected by Vereecke et al [6,17,22,23,29], Vereecke & Aerts [26], Channon et al [27,30] and Vereecke & Channon [28] will be combined in a new synthesis. (A short synopsis of the Material and Methods of these papers is included as the electronic supplementary material.…”

Understanding the evolution of the windlass mechanism of the human foot from comparative anatomy: Insights, obstacles, and future directions

“…Great apes do have bouts of bipedalism, but more often than not they walk on all fours when on the ground. Gibbons have a very mobile foot and do not exhibit a windlass mechanism, but have an Achilles tendon comparable to that of modern humans in its relatively long length (Vereecke et al, ; Vereecke and Aerts, ; Sellers et al, ; Myatt et al, ) and therefore potential to store and release energy during bipedal gait (Vereecke et al, ; Vereecke and Channon, ). This shared trait or convergence between humans and gibbons may have been selected for independently in these lineages for the purpose of making human locomotion on two feet more efficient; by saving energy and/or increasing jumping performance in gibbons.…”