Abstract
The purpose of this study was to examine the test-retest reliability for the real time ultrasonic measurement method that is used to determine the stiffness of the Achilles tendon. Twenty-one healthy men and women aged 20–50 years took part in the study. The subjects underwent three identical test sessions held seven days apart. The lengthening of the tendon during maximal isometric plantar flexion was determined using ultrasonography. A dynamometer was used to measure torque output during isometric plantar flexion. The relationship between the muscle force and the elongation of the tendon was calculated to become a measure of the stiffness of the Achilles tendon. The ICC for the stiffness of the right and the left Achilles tendon was 0.80 and 0.82 respectively, indicating a good reliability. The results demonstrate that this technique is reliable for the evaluation of the elastic properties of the Achilles tendon. This may be clinically important in the assessment of tendon properties.