Saul Yudelowitz BSc (Hons)
The Achilles tendon is placed under a significant load from the tension generated by the Gastronomies and Soleus. While there is no doubt that genetics to a degree can affect the tendon some athletes are more prone to inflammation and rupture that others, however biomechanics has a significant effect on the functioning of the tendon. I use the word tension here in the same manner it is applied to biomechanics and engineering. An increase in tension is when tissue increases its length under load relative to its original length.
The Achilles tendon twists laterally allowing the majority of the fibres from the Gastrocnemius to insert on the posterolateral surface of the Calcaneus. The fibres from the Soleus insert mainly on the posteromedial surface of the Calcaneus. The twisting becomes most pronounced at about 5cm above the Calcaneus.
From a biomechanical point, twisting of tissue has a significant affect on the overall strength and this twisting is found in many other areas of the body. Biomechanics stems from engineering and engineering has proved many decades ago that twisting increases the overall strength; this is why rope is made up of many strands that twist around one another.
While the point of this article is not to prove the above it is about getting therapists to look at patients from a more holistic approach when rehabilitating Achilles tendonosis.
Having treated professional athletes for the good part of a decade I have consistently found that athletes who have internally rotated hips will be more predisposed to Achilles tendonosis. This is because as the tendon descends to the Calcaneus it twists laterally. By internally rotating the hips the tendon becomes less twisted or untwisted, from the top down. The twisting of the tendon adds significant strength and so internally rotated hips decrease the overall strength of the tendon.
From a biomechanical perspective we are supposed to have the feet and knees turned out, this is because of the antroversion of the hip. The degree of hip antroversion should match the knee and foot. This allows for correct function of many muscles in particular the Gluteal Maximums. While I acknowledge that internally rotated hips are not the sole cause of all Achilles tendonosis there are other factors to consider. As stated above this article is to assist in a more holistic approach to rehabilitation.
I leave you with one thought apart from this to consider. Since an increase in tension of a muscle is associated with an eccentric contraction, are the typical stretches we see in the clinic setting a stretch or just an increase in tension?
Haiquin Rong. The Structure of Human Achilles tendon and its Biomechanical Significance. Department of Anatomy, Qingdao Medical College. P.R. China Web: w4.ub.uni-konstanz.de/cpa/article/viewFile/2896/2742.
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