Method and strain rate dependence of Achilles tendon stiffness

Theis, Nicola ORCID: 0000-0002-0775-1355, Mohagheghi, Amir A and Korff, Thomas (2012) Method and strain rate dependence of Achilles tendon stiffness. Journal of Electromyography and Kinesiology, 22 (6). pp. 947-953. doi:10.1016/j.jelekin.2012.06.004

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Tendon stiffness is calculated by dividing changes in tendon force by tendon elongation. For this purpose, participants are commonly asked to perform a maximal muscle contraction (‘‘active’’ method). Alternatively tendon elongation can be achieved by means of a passive joint rotation (‘‘passive’’ method). The purpose of this study was to compare Achilles tendon stiffness obtained from both methods across different tendon strain rates. Twenty adults performed a series of ramped maximum isometric plantarflexions of different durations. Passive ankle rotations of different angular velocities were also performed. Achilles tendon stiffness was obtained from a combination of motion analysis, isokinetic dynamometry and ultrasonography and compared across methods at three strain rates. At all strain rates, tendon stiffness obtained from the active method was 6% greater compared to the passive method. In spite of this systematic bias, there was good agreement between the methods. Intraclass correlation coefficients were greater than 0.98, and more than 95% of data points fell into the 95% confidence intervals. This agreement will be acceptable in many research contexts. We also found a linear increase in tendon stiffness with increasing strain rate, which must be taken into consideration when interpreting or reporting tendon stiffness.

Item Type: Article
Article Type: Article
Uncontrolled Keywords: Tendon; Velocity; Strain rate
Subjects: Q Science > QP Physiology
Divisions: Schools and Research Institutes > School of Education and Science
Research Priority Areas: Health, Life Sciences, Sport and Wellbeing
Depositing User: Nicola Theis
Date Deposited: 02 Nov 2017 16:31
Last Modified: 31 Aug 2023 09:10

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