Optimal pennation angle of the primary ankle plantar and dorsiflexors: variations with sex, contraction intensity, and limb

Ultrasonography was used to measure the pen-nation angle of the human tibialis anterior (TA), lateral gastrocnemius (LG), medial gastrocne-mius (MG), and soleus (Sol). The right and left legs of 8 male and 8 female subjects were tested at rest and during maximum voluntary contrac-tion (MVC). Joint angles were chosen to control muscle tendon lengths so that the muscles were near their optimal length within the length– tension relationship. No differences in pennation angle were detected between the right and left legs. Another consistent finding was that the pen-nation angle at MVC was significantly greater than at rest for all muscles tested. Optimal penna-tion angles for the TA, MG, and Sol were signifi