Cochrane review 2011 - link here

O'Neill, S et al 2014 paper on Soleus stength deficits - link here.

Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb. Heinemeier KM, Schjerling P, Heinemeier J, Magnusson SP, Kjaer M.FASEB J. 2013 May;27(5):2074-9. doi: 10.1096/fj.12-225599. Epub 2013 Feb 11. 

Newsarticle link to Carbon 14 study