Exercise can be a dose of good medicine

By JULIE DEARDORFF CHICAGO TRIBUNE CHICAGO — On a recent Wednesday night, Cindy Gerstner, 42, strapped her feet into a rowing machine and began gliding back and forth with all the energy she could muster. This wasn’t just a workout for Ms. Gerstner, whose stage IV breast cancer has spread to her brain, lungs, bones, and liver. It was a 40-minute dose of medicine. “It’s part of my treatment plan …