Training-induced increase in Achilles tendon stiffness affects tendon strain pattern during running

PeerJ

article

Amelie Werkhausen¹  Neil J. Cronin²  Kirsten Albracht³  Gøran Paulsen⁵  Askild V. Larsen¹  Jens Bojsen-Møller¹  Olivier R. Seynnes¹ 

[1] Department of Physical Performance, Norwegian School of Sport Sciences;Neuromuscular Research Centre, Faculty of Sport and Health Sciences, University of Jyväskylä;Institute of Biomechanics and Orthopedics, German Sport University Cologne;Department of Medical Engineering and Technomathematics, Aachen University of Applied Sciences;The Norwegian Olympic and Paralympic Committee and Confederation of Sports

关键词: Achilles tendon;    Stiffness;    Running;    Tendon properties;    Architectural gear ratio;    Gastrocnemius;    Soleus;   

DOI  :  10.7717/peerj.6764

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

BackgroundDuring the stance phase of running, the elasticity of the Achilles tendon enables the utilisation of elastic energy and allows beneficial contractile conditions for the triceps surae muscles. However, the effect of changes in tendon mechanical properties induced by chronic loading is still poorly understood. We tested the hypothesis that a training-induced increase in Achilles tendon stiffness would result in reduced tendon strain during the stance phase of running, which would reduce fascicle strains in the triceps surae muscles, particularly in the mono-articular soleus.MethodsEleven subjects were assigned to a training group performing isometric single-leg plantarflexion contractions three times per week for ten weeks, and another ten subjects formed a control group. Before and after the training period, Achilles tendon stiffness was estimated, and muscle-tendon mechanics were assessed during running at preferred speed using ultrasonography, kinematics and kinetics.ResultsAchilles tendon stiffness increased by 18% (P < 0.01) in the training group, but the associated reduction in strain seen during isometric contractions was not statistically significant. Tendon elongation during the stance phase of running was similar after training, but tendon recoil was reduced by 30% (P < 0.01), while estimated tendon force remained unchanged. Neither gastrocnemius medialis nor soleus fascicle shortening during stance was affected by training.DiscussionThese results show that a training-induced increase in Achilles tendon stiffness altered tendon behaviour during running. Despite training-induced changes in tendon mechanical properties and recoil behaviour, the data suggest that fascicle shortening patterns were preserved for the running speed that we examined. The asymmetrical changes in tendon strain patterns supports the notion that simple in-series models do not fully explain the mechanical output of the muscle-tendon unit during a complex task like running.

【 授权许可】

CC BY