Achilles tendon echo intensity changes across a five-day training cycle in elite athletes.

The aim of this study was to determine if a five-day training cycle in professional sports team athletes caused acute and subacute alterations in Achilles tendon echo intensity. The study included 24 males, 24 females of football, handball, volleyball teams from the top national leagues. During their respective competition periods, eight players from each team were monitored in every training session over a five-day training cycle. It involved monitoring Achilles tendon echo intensity, cross-sectional area with ultrasound, subjective feelings of fatigue, perceived exertion throughout the training cycle. The results revealed a significant acute, subacute effect on echo intensity at distal (P < 0.001), middle (P < 0.001), proximal (P < 0.001) Achilles tendon locations. The acute effect had a significant impact on the subacute changes in echo intensity at all locations (P < 0.001). A significant interaction of athletes' biological sex, the acute effect was only observed in distal Achilles tendon (P = 0.013). The study revealed a significant decrease in Achilles tendon echo intensity following team sports training sessions for males and females. A consistently reduced echo intensity of the Achilles tendon during the five-day training cycle suggests that repetitive loading likely induces structural changes in the tendon.