ReviewEvolution of the Achilles tendon: The athlete's Achilles heel?
Section snippets
How the tendon has evolved
The development of the Achilles tendon helped facilitate the evolution from apes with a herbivorous diet to early hominins which had an omnivorous diet [3]. The Achilles tendon is absent or short in apes, meaning that their calf muscles extend right down to their tarsal bones [7]. This gave early apes the ability to display arboreal locomotion which corresponded with their herbivorous diet [3]. However the previously abundant food supplies in their environment became sparser and seasonal and so
The tendon in athletes
Some studies have observed that the Achilles tendons in athletes are much thicker than compared to the tendons in subjects who are less active [10]. Emerson et al. found using ultrasonography, that the thickness of the Achilles tendons in gymnasts was significantly higher in five of the six measures carried out than the control group [10]. Ying et al. compared the thickness and cross-sectional area of the Achilles tendons belonging to subjects who frequently exercised (two hour exercise
Why is the tendon the way it is?
The plantaris muscle has a long delicate tendon which is stretched during walking and running exactly like a length of elastic [13]. An advantage of the Achilles tendon is that it is an important elastic energy store [13]. The plantaris tendon is able to return over ninety percent of the energy stored in this way during walking and running [13]. This is an important mechanism for camels and kangaroos in their locomotion [13]. During gait, kinetic energy lost at one stage of a stride is stored
Is it here to stay?
The debate about the future existence of the Achilles tendon has been conjured due to its vulnerability to injury. It does not seem comprehensible that a multifunctional tendon which is vital in bipedal locomotion should be so prone to damage, and even more prone in physically active and fitter humans. One study found that athletes who obtain an Achilles tendon injury can be for them career altering. It found that out of all the national American football players who sustained an Achilles
How will it continue to evolve?
If the Achilles tendon has more evolutionary flaws than advantages for fast bipedal locomotion, then maybe it has no more evolutionary potential to offer. As already discussed the Achilles tendon cannot keep getting longer in length, as this would be detrimental to bipedal locomotion. However maybe there is room for evolution to change the insertion site of the tendon or to bring another mechanism instead of the Achilles tendon in order to give efficient fast bipedal locomotion. Local tendons
Conclusion
In summary the Achilles tendon is here to stay in our anatomy. This is not only because of the evolutionary advantages its possesses such as facilitating fast bipedal locomotion, acting as a spring and shock absorber during gait, supplying an energy saving mechanism during movement and being the strongest tendon in the body. Another valid reason why this tendon will stay in our anatomy for many generations to come is because the rate of evolution in the human species is very slow [37].
Conflict of interest
None.
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A mathematical model characterising Achilles tendon dynamics in flexion
2017, Mathematical BiosciencesCitation Excerpt :The mechanical properties of the Achilles tendon allow it to store and transmit elastic strain energy during fast locomotion and other movements [7]. That is why it is described as an energy-saving mechanism and a spring and shock absorber during gait [8]. It has been demonstrated through measurements of the mechanical properties of the Achilles tendon, that there is a variation in the elastic properties and the stiffness of the tendon between individuals [9,10].
A mathematical model of the achilles tendon in humans
2015, IFAC-PapersOnLinePartial rupture of the Achilles tendon during a simulated fire ground task: Insights obtained from a case report for the prevention and reporting ofmusculoskeletal injury
2013, Clinical BiomechanicsCitation Excerpt :This finding supports previous recommendations (Kumar, 2001; McGill, 1997), stating that focusing on a single variable (e.g., peak force), joint or culminating event may not provide a comprehensive understanding needed to avert future injury. The AT is one of the most frequently injured tendons in the human body (Wren et al., 2001), even though it is considered to be one of the strongest and thickest tendons (Malvankar and Khan, 2011). The majority of AT ruptures are seen in men, with peak incidence occurring between 30 and 50 years of age (Leppilahti and Orava, 1998).
The Pathogenesis of Tendon Microdamage in Athletes: The Horse as a Natural Model for Basic Cellular Research
2012, Journal of Comparative PathologyCitation Excerpt :Up to 29% of patients with AT injuries may require surgery (Zafar et al., 2009); time for a return to activity varies from 6 weeks to almost 10 months depending on the complexity and chronicity of the injury, and re-rupture rates of 2–12% have been reported (Molloy and Wood, 2009; Saxena et al., 2011). The functional equivalence of the SDFT and AT is largely due to their pivotal role in saving energy during high-speed locomotion, by reducing muscular work (Biewener, 1998; Malvankar and Khan, 2011). Most tendons (‘positional’ tendons) simply connect skeletal muscle and bone, stabilizing and moving joints.
Long-term results and complication following Achilles tendon rupture repair
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