A previously healthy 40-year old man is brought to the emergency department 1 hour after the onset of severe pain in his left leg while playing tennis. He is found to have ruptured the left Achilles tendon and undergoes operative repair and long leg cast immobilization. Six months later, the left calf shows a 2-cm decrease in circumference compared with the right calf. Which of the following is the most likely cause of this decrease?
A. Decreased glycogen synthesis B. Decreased myosin light chain phosphatase activity C. Increased phosphatidyl degradation D. Increased protein degradation E. Mitochondria damage F. Necrosis of muscle fibers