Walking test can ID heart-lung fitness, mortality risk

"If you're middle-aged or older, a 10-minute walking test can give you and your doctor a pretty clear picture of whether you are at higher risk of dying during the next few years compared with other people your age, according to a large new analysis of data showing that cardiorespiratory fitness is intimately linked with the risk of dying of just about any cause. However, you probably won't get this exercise test unless you ask for it. The exercise stress test - or, in medical parlance, the graded exercise test - measures your cardiorespiratory fitness, or how well your heart, lungs, muscles, and blood vessels work together to use oxygen and produce energy. There are several ways to do the test, but it basically involves walking or running on a treadmill at progressively steeper inclines or faster speeds under medical supervision" - CNN