Running, jogging, swimming, cycling, and other physical activities that use your cardiovascular system (lungs and heart) for a long time can make your body tired. Cardiovascular endurance is how well your body can keep up with these activities for a long time. Your heart and lungs work together to give your muscles the oxygen they need to do their jobs. Many trainers prefer the Step Test to the Cooper Run because it is a better test of cardiovascular endurance. You run as far as you can in 12 minutes (stepping onto a platform for 5 minutes). Both are good ways to measure a person's cardiovascular endurance.