From the Skeptical Scalpel blog: http://skepticalscalpel.blogspot.com/2013/10/hospitalized-elderly-patients-spend-too.html

The paper was a study of the activity of elderly patients who spent about 6 hours per day on their feet before they were admitted. Failure to walk around in the hospital had significant negative effects on the activity levels of patients for as long as two years after discharge from the hospital.
That brings up the question, why didn’t they walk more?
According to the New York Times, “Even when physicians recognize the hazards of immobility and write orders that include ambulation, overworked staff can’t always find the time.”
A lack of a minimum standard of care means nurses may be trying to care for too many patients at one time, and patients may lie in bed without seeing a nurse for some time. Even if they’re in pain or need to be ambulatory as part of their recovery plan.
Read more at the Skeptical Scalpel
Story also at the New York Times