The Achilles tendon: 3 is better than 1
The Achilles tendon, the strongest tendon in the body, is not just one tendon, but actually 3 tendons intertwined into one!
Fibres originating from the soleus muscle, and the medial & lateral heads of the gastrocnemius muscle, twist around each other as they combine & attach into the back of the heel. Sometimes the plantaris can also be a part of the Achilles tendon, making it 4 in 1! The degree of twisting can also differ between individuals, which may make some prone to developing tendinopathy.
Why is this important clinically?
Firstly, with movement, there is actually gliding of these intertwined tendons, & it is hypothesized that excessive friction between these fibres may contribute to Achilles tendinopathy. (Franz et al 2016, Franz et al 2015).
It is therefore worthwhile incorporating into rehab, a variety of exercises that stress the 3 different components of the Achilles tendon which could include a mix of:
Bent knee calf raise to target the soleus (seated or standing with the knee bent more than 60 degrees)
Straight leg calf raise to bias the gastrocnemius
Calf raise with Internal & External rotation to bias more the medial & lateral components of the gastrocs
If you are having Achilles troubles, please don't hesitate to contact us at www.healthhp.com.au
Franz, J. R. and D. G. Thelen (2016). "Imaging and simulation of Achilles tendon dynamics: Implications for walking performance in the elderly." Journal of biomechanics 49(9): 1403-1410. Franz, J. R., et al. (2015). "Non-uniform in vivo deformations of the human Achilles tendon during walking." Gait Posture 41(1): 192-197.
Franz, J. R. and D. G. Thelen (2015). "Depth-dependent variations in Achilles tendon deformations with age are associated with reduced plantarflexor performance during walking." J Appl Physiol (1985) 119(3): 242-249.
Pekala, P. A., et al. (2017). "The twisted structure of the Achilles tendon unravelled: A detailed quantitative and qualitative anatomical investigation." Scand J Med Sci Sports 27(12): 1705-1715.