Decrease in the number of individual muscle fibers in the left gastrocnemius

Decrease in blood flow to the muscle caused by constriction from the cast

Temporary reduction in actin and myosin protein synthesis

Increase in glycolytic activity in the affected muscle

A 17-year-old soccer player sustained a fracture to the left tibia. After her lower leg has been in a cast for 8 weeks, she is surprised to find that the left gastrocnemius muscle is significantly smaller in circumference than it was before the fracture. What is the most likely explanation?