Figure 2.

Model for human tendon tissue formation and turnover. Dotted line shows the 0–17 yr moving average of the ¹⁴C level in the atmosphere, representing the relation between calendar year and the average atmospheric ¹⁴C level during the subsequent 17 yr (e.g., value in 1960 corresponds to average atmospheric ¹⁴C between 1960 and 1977). The curve reproduces relatively well the observed levels of ¹⁴C in Achilles tendons samples (gray squares), suggesting that the tendon tissue ¹⁴C was incorporated during height growth (0–17 yr) and that tissue replacement during adulthood was very limited. The large black circle indicates three tendon samples with deviating ¹⁴C concentrations, potentially due to abnormally high turnover during later periods in life with low atmospheric ¹⁴C. The dataset contained three clear outliers, indicated as #25, #28, and #30.