Force-sharing within the triceps surae: an Achilles heel in Achilles tendinopathy

We compared the distribution of force among the three heads of the triceps surae between 21 participants with
Achilles tendinopathy and 21, case-wise paired, asymptomatic controls.
Ultrasonography
was used to measure muscle volume, fascicle length, pennation angle and
subtendon length at rest. Muscle activation was estimated using surface electromyography
during maximal and submaximal isometric plantarflexion
tasks. The product of normalized activation,
physiological cross-sectional area (PCSA), and the cosine of the pennation
angle was considered as an index of individual muscle force. Displacement of the distal myotendinous
junction of each muscle was measured during the submaximal contractions.
All processed data are made available here.