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Substantial Achilles adaptation following strength training has no impact on tendon function during walking
1Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
Plos One
|July 29, 2021
Summary
Twelve weeks of strength training significantly increased Achilles tendon (AT) stiffness. However, this adaptation did not alter AT function during walking, suggesting stiffness changes may not apply across the entire force-elongation relationship.
Area of Science:
- Biomechanics
- Musculoskeletal Adaptations
- Tendon Physiology
Background:
- Tendons are mechanically responsive tissues crucial for locomotion.
- Tendon stiffness influences energy efficiency during activities involving the stretch-shortening cycle.
- Understanding how training affects tendon function in vivo is vital.
Purpose of the Study:
- To investigate the in vivo function of the Achilles tendon (AT) during walking after a training intervention.
- To determine if increased AT stiffness, induced by strength training, impacts AT function during gait.
Main Methods:
- 14 participants underwent 12 weeks of isometric plantarflexor strength training, increasing AT stiffness by ~31%.
- 3D motion capture and ultrasound imaging assessed kinematics, kinetics, and muscle-tendon junction displacement during walking before and after training.
- Statistical analysis examined changes in AT mechanical properties and gait parameters.
Main Results:
- Despite significant increases in AT stiffness measured during maximal voluntary contractions, AT function during walking (including force, stress, strain, stiffness, and energy measures) remained unchanged.
- Gait kinematics, tendon strain, velocity, work, power, and muscle activity during the stance phase also showed no significant changes post-intervention.
- Achilles tendon stiffness measured during walking did not change with training.
Conclusions:
- Substantial increases in Achilles tendon stiffness achieved through strength training did not translate to altered tendon function during walking.
- The lack of change in walking-specific AT stiffness suggests adaptations may not affect the entire force-elongation curve.
- These findings provide a foundation for understanding tendon adaptation and may explain variability in previous intervention outcomes.
