Effects of high loading by eccentric triceps surae training on Achilles tendon properties in humans.
Level 4 - case-series / case-control
Uncontrolled longitudinal pre-post intervention study in human volunteers
PubMed 29858689 · doi:10.1007/s00421-018-3904-1
What was done
Human volunteers completed a 12-week high-load eccentric triceps surae plantar flexion training program. Achilles tendon morphological and mechanical properties were evaluated before training and after 4, 8, and 12 weeks of training. Ultrasonography was used to measure tendon cross-sectional area (CSA), length, and elongation during voluntary plantar flexion torque to determine force-elongation and stress-strain relationships.
What was found
After 12 weeks of training, maximum isometric force increased by 49%, tendon CSA increased by 17%, tendon stiffness increased by 82%, and Young's modulus increased by 86%, while tendon length, maximal elongation, and maximal strain were unchanged. Statistically significant increases were detected at 4 weeks for stiffness (51% increase) and Young's modulus (87% increase), whereas significant increases in CSA were first detected at 8 weeks (15% increase).
Why it matters
This study delineates the temporal sequence of tendon adaptations, indicating that material property adaptations precede gross morphological hypertrophy during chronic high-load tendon loading.
Limits
The abstract does not report sample size, participant demographics (such as age, sex, or training status), baseline values, or dispersion metrics (such as standard deviations or confidence intervals). There was no separate control group.
Cited by
- supports Emphasizing the eccentric phase of resistance exercises increases tensile strength in tendons.