How to measure fitness

Exercise physiologists gauge fitness by looking at your "VO2 max." That's the amount of oxygen your heart can pump throughout your body when you move. (If you're curious, the V is for volume, the O for oxygen.)

You can have your VO2 measured by an exercise physiologist or other fitness expert, who will perform a simple test to see how your heart rate responds as you add exercise intensity by working harder. You'll come away with a target heart rate matched to your current fitness and a plan for how to keep improving.

You can also gauge your VO2 max yourself by looking at how easy or hard it is for you to perform common daily activities.