Gastrocnemius tendon length and strain are different when assessed using straight or curved tendon model

The present study investigated the effects of tendon curvature on measurements of tendon length using 3D-kinematic analysis. Curved and straight tendon models were employed for assessing medial gastrocnemius tendon length and strain during hopping (N = 8). Tendon curvature was identified using small reflective markers placed on the skin surface along the length of the tendon and a sum of vectors between the markers from the calcaneous up to the marker at the origin of tendon was calculated. The straight tendon was defined as a length of vector from the calcaneous to the marker at the origin of tendon. The curved tendon method yielded 5.0 ± 1.3 mm longer tendon (p < 0.001) than the straight …