Recovery of the dog quadriceps after 10 weeks of immobilization followed by 4 weeks of remobilization

Skeletal muscle fiber areas were measured in three heads of the dog quadriceps after 10 weeks of immobilization followed by 4 weeks of remobilization. Two‐way analysis of variance demonstrated a significant decrease in both type 1 (p < 0.005) and type 2 (p < 0.001) fiber area. However, there was no significant difference among the three heads of the quadriceps (p > 0.2). Although muscle fiber areas had not returned to control levels following remobilization, the area fraction of perimysial and epimysial connective tissue was not significantly different from control values (p > 0.15). These data suggest that although the degree of muscle atrophy following 10 weeks of immobilization is severe and muscle specific, following 4 weeks of remobilization, muscles uniformly recover to about 70% of control values.