Jeam Marcel Geremia1,2, Bruno Manfredini Baroni3, Maarten Frank Bobbert4, Rodrigo Rico Bini5, Fabio Juner Lanferdini6, Marco Aurélio Vaz6. 1. Laboratório de Biomecânica (LABIOMEC), Centro de Educação Física e Desportos, Universidade Federal de Santa Maria (UFSM), Avenida Roraima, 1000-Prédio 51-Bairro Camobi, Santa Maria, RS, CEP 97105-900, Brazil. jeam_geremia@hotmail.com. 2. Laboratório de Pesquisa do Exercício, Escola de Educação Física, Fisioterapia e Dança, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. jeam_geremia@hotmail.com. 3. Departamento de Fisioterapia, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil. 4. Department of Human Movement Sciences, Faculty of Behavioral and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands. 5. La Trobe Rural Health School, La Trobe University, Bendigo, Australia. 6. Laboratório de Pesquisa do Exercício, Escola de Educação Física, Fisioterapia e Dança, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Abstract
PURPOSE: To document the magnitude and time course of human Achilles tendon adaptations (i.e. changes in tendon morphological and mechanical properties) during a 12-week high-load plantar flexion training program. METHODS: Ultrasound was used to determine Achilles tendon cross-sectional area (CSA), length and elongation as a function of plantar flexion torque during voluntary plantar flexion. Tendon force-elongation and stress-strain relationships were determined before the start of training (pre-training) and after 4 (post-4), 8 (post-8) and 12 (post-12) training weeks. RESULTS: At the end of the training program, maximum isometric force had increased by 49% and tendon CSA by 17%, but tendon length, maximal tendon elongation and maximal strain were unchanged. Hence, tendon stiffness had increased by 82%, and so had Young's modulus, by 86%. Significant changes were first detected at post-4 in stiffness (51% increase) and Young's modulus (87% increase), and at post-8 in CSA (15% increase). CONCLUSIONS: Achilles tendon material properties already improved after 4 weeks of high-load training: stiffness increased while CSA remained unchanged. Tendon hypertrophy (increased CSA) was observed after 8 training weeks and contributed to a further increase in Achilles tendon stiffness, but tendon stiffness increases were mostly caused by adaptations in tissue properties.
PURPOSE: To document the magnitude and time course of human Achilles tendon adaptations (i.e. changes in tendon morphological and mechanical properties) during a 12-week high-load plantar flexion training program. METHODS: Ultrasound was used to determine Achilles tendon cross-sectional area (CSA), length and elongation as a function of plantar flexion torque during voluntary plantar flexion. Tendon force-elongation and stress-strain relationships were determined before the start of training (pre-training) and after 4 (post-4), 8 (post-8) and 12 (post-12) training weeks. RESULTS: At the end of the training program, maximum isometric force had increased by 49% and tendon CSA by 17%, but tendon length, maximal tendon elongation and maximal strain were unchanged. Hence, tendon stiffness had increased by 82%, and so had Young's modulus, by 86%. Significant changes were first detected at post-4 in stiffness (51% increase) and Young's modulus (87% increase), and at post-8 in CSA (15% increase). CONCLUSIONS: Achilles tendon material properties already improved after 4 weeks of high-load training: stiffness increased while CSA remained unchanged. Tendon hypertrophy (increased CSA) was observed after 8 training weeks and contributed to a further increase in Achilles tendon stiffness, but tendon stiffness increases were mostly caused by adaptations in tissue properties.
Entities:
Keywords:
Eccentric training; Human tendon stiffness; Myotendinous junction; Ultrasound
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