Effects of an eccentric training protocol on mechanical properties of the ankle joint in young soccer players

Muscle tone in young soccer players is key for optimizing performance and reducing injury risk. This study evaluated an 8-week predominantly eccentric training protocol's impact on triceps surae/Achilles tendon mechanical properties and ankle dorsiflexion. Thirty players were randomized to an intervention group (IG, n = 15; additional 2 weekly eccentric sessions) or control group (CG, n = 15; regular training). Mechanical properties were assessed via myotonometry and ankle dorsiflexion via the Weight-Bearing Lunge Test. Results at 8 weeks showed in IG vs. CG: 1) Reduced active tension (muscle frequency: lateral gastrocnemius left d = −0.82, right d = −1.40; medial gastrocnemius left d = −1.29, right d = −1.30; soleus right d = −0.80; Achilles tendon left d = −0.68; all p < 0.05). 2) Decreased stiffness in lateral gastrocnemius right (d = −1.12) and medial gastrocnemius (left d = −0.68, right d = −0.86; p < 0.05). 3) Increased passive tension properties: creep in lateral gastrocnemius right (d = 0.94; p < 0.05) and medial gastrocnemius (left d = 0.79, right d = 0.97; p < 0.05); relaxation in medial gastrocnemius (left d = 0.64, right d = 1.03; p < 0.05). 4) Reduced ankle dorsiflexion in the right leg (d = −0.68; p < 0.05). These findings indicate that eccentric training modulates musculotendinous mechanical properties, potentially influencing neuromechanical factors related to injury-related mechanisms.