Achilles tendon and triceps surae muscle properties in athletes

Purpose The aim of this study was to investigate internal Achilles tendon (AT) displacement, AT shear wave velocity (SWV), and triceps surae (TS) muscle shear modulus in athletes. Methods Internal AT displacement was assessed using ultrasound during isometric contraction. Shear wave elastography was used to assess AT SWV (m × s –1 ) at rest and TS muscle shear modulus (kPa) during passive ankle dorsiflexion. Results A total of 131 athletes participated in this study. Athletes who had not exercised within two days had greater AT non-uniformity and mean anterior tendon displacement, and lower SWV at the proximal AT measurement site (mean difference [95% CI]: 1.8 mm [0.6–2.9], p = 0.003; 1.6 mm [0.2–2.9], p = 0.021; – 0.9 m × s –1 [– 1.6 to – 0.2], p = 0.014, respectively). Male basketball players had a lower mean AT displacement compared to gymnasts (– 3.7 mm [– 6.9 to – 0.5], p = 0.042), with the difference localised in the anterior half of the tendon (– 5.1 mm [– 9.0 to – 1.1], p = 0.022). Male gymnasts had a smaller absolute difference in medial gastrocnemius-minus-soleus shear modulus than basketball players (59.6 kPa [29.0–90.2], p