Many Americans spend a good portion of the day sitting. Between a 40-hour work week and a commute, time spent sitting adds up, as do the associated health problems. Enter the standing desk. A popular option, the standing desk may be an effective way to combat risk factors associated with sitting. But it's not just sitting that gets a bad rap. Standing for long periods of time can also take a toll on the body. Nurses, teachers and other professionals often complain of back pain and other stress