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. Author manuscript; available in PMC: 2020 Jun 1.
Published in final edited form as: J Appl Biomech. 2019 Apr 10;35(3):182–189. doi: 10.1123/jab.2018-0297

Figure 2.

Figure 2.

(A) Group mean data for soleus muscle stiffness, kM, as given by the relation between soleus muscle force (FSOLEUS) and soleus muscle length (LSOLEUS). LSOLEUS gives length change along the line of action of the soleus muscle, equal to the length of the fascicle (LFASCICLE) multiplied by the cosine of pennation angle (θ). (B) Group mean data for ankle joint quasi-stiffness, kA, at each soleus activation level (α), given by the relation between net ankle moment and ankle joint angle (dorsiflexion positive). (C) Group mean kM and kAas a function of soleus activation. Sensitivity to altered activation was calculated as the slope of each region of stiffness versus activation (group mean values shown). Bars on all panels represent standard error of the mean.