Eccentric Training Effects on Functionality and on Triceps Surae Neuromechanical Properties After Achilles Tendon Surgical Repair

Detailed Summary

Early rehabilitation protocols have been studied in Achilles tendon (AT) rupture patients, but deficits in tendon biomechanical properties have been observed several years after the injury. AT rupture patients are unable to return to their previous levels of physical activity. They present deleterious adaptations in the plantar flexor muscles that lead to functional deficits, and deficits in the tendon's structural and mechanical properties. Eccentric contractions have been suggested to recover these muscle properties. This contraction is known to produce higher force compared to isometric and concentric contractions, and increases tendon stiffness. However, there is a lack of studies showing the effects of the eccentric training in AT rupture rehabilitation. We want to know if an isokinetic eccentric training program will determine the desired adaptations on triceps surae muscle-tendon unit's properties in patients subjected to the AT surgical repair. More specifically, the aim of this study is verifying the effects of a 12-week eccentric training program on triceps surae muscle-tendon unit's properties in subjects that were subjected to the AT surgical repair. 30 subjects will be randomized in two groups: (1) isokinetic eccentric training; and (2) traditional eccentric training control group. All participants will be submitted to a four-week control period, followed by a 12-week period of training for the plantar flexor muscles. Neuromuscular system properties, AT biomechanical properties and functional tests will be evaluated. Participants will be evaluated in four moments: at baseline; after 4, 8 and 12 weeks of rehabilitation. Tendon mechanical (stiffness, stress, strain), material (Young's modulus) and morphological (cross-sectional area and tendon length) properties; muscle architecture (thickness, pennation angle and fascicle length); and functional tests (heel rise resistance and height) will be analyzed between groups and periods. Effects and interactions will be analyzed with ANOVA two-way. Clinical effects will be analyzed using effect size and magnitude-based inferences.

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