Mariam is an active 69-year-old. She leads the pool aerobic exercise group in the senior retirement community that she and her husband moved to 3 years ago. She walks 2 miles each morning and eats a healthy, balanced diet. She is from a family with longevity and trusts she will have good health well into her 90s. As Mariam is walking to her exercise class, she steps off the curb and falls. She is taken to the emergency room and diagnosed with a fractured hip. She must be on bedrest and in traction for a week before surgery is scheduled. During that time, the pain is significant and she requires a large amount of pain medicine. Which factors contribute to her immobility