When you’re staring petrified at the new Resident Evil movie, or breathlessly following along to a vintage Jane Fonda aerobics video, what happens to your blood flow? PhD candidate Joseph C. Muskat and a group from Purdue University created algorithms that model how healthy young adults respond to fear- and exercise-induced stress. The simulations allow scientists to probe parts of the cardiovascular system individually and measure blood pressure and flow patterns—difficult feats in living, breathing humans.