Fig. 2. Relationship between fiber diameter and peak Ca²⁺-activated isometric force (P₀) for subject B of the 17-day STS-78 shuttle flight. Each symbol represents the results from a single soleus fiber. Type I fibers, shaded circles; type IIa fibers, filled triangles; type I/IIa fibers, open triangles (redrawn from) (Widrick et al., 1999).