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Updated: Jan 25, 2026
08:11
Ultrasound Tissue Characterization of Human Achilles Tendon by Stability Quantification of Echo Patterns
Published on: September 5, 2025
467
Training-induced increase in Achilles tendon stiffness affects tendon strain pattern during running.
Amelie Werkhausen1, Neil J Cronin2, Kirsten Albracht3,4
1Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
Peerj
|May 16, 2019
Summary
Training increased Achilles tendon stiffness, altering its recoil behavior during running. However, muscle fascicle shortening patterns remained consistent, suggesting complex muscle-tendon unit mechanics during locomotion.
Area of Science:
- Biomechanics
- Human Movement Science
- Sports Medicine
Background:
- The Achilles tendon's elasticity is crucial for energy utilization during running.
- Chronic loading effects on tendon mechanical properties are not fully understood.
- Investigating how increased Achilles tendon stiffness impacts running mechanics is essential.
Purpose of the Study:
- To test if increased Achilles tendon stiffness reduces tendon and muscle strain during running.
- To understand the adaptation of the triceps surae muscles to altered tendon properties.
Main Methods:
- 10-week isometric plantarflexion training program for one group, control for another.
- Assessed Achilles tendon stiffness, muscle-tendon mechanics during running via ultrasonography, kinematics, and kinetics.
Main Results:
- Training increased Achilles tendon stiffness by 18%.
- Tendon recoil decreased by 30% during running, with no change in elongation or force.
- Neither gastrocnemius medialis nor soleus fascicle shortening was affected by training.
Conclusions:
- Increased Achilles tendon stiffness alters tendon recoil during running.
- Muscle fascicle shortening patterns were preserved at the tested running speed.
- Asymmetrical changes in tendon strain suggest limitations of simple in-series models for muscle-tendon unit function.
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