The researchers examined the men and asked them detailed questions about their level of physical activity. The men also completed a special test that measured how physically fit they were by monitoring them during exercise. The researchers did ultrasound tests, which show detailed images of the men's carotid arteries, both at the start of the study and again 4 years later. These images made it possible to measure the amount of narrowing from atherosclerosis. The researchers tested the relationship between the amount of atherosclerosis that developed over the 4 years and the men's physical fitness levels.