Your cardio fitness index is related to your VO2max. V02max is how much oxygen your body uses when you’re exercising as hard as you can. It’s the best known way of measuring cardiovascular fitness. When calculating your cardio fitness index, we also take into account your resting heart rate, age, gender, and weight.
To find out where you are on the cardio fitness index wear your watch for a full week, and make sure to take some long walks during that week. We’ll recalculate your cardio fitness index each week, using your most up-to-date health data.
Note: always consult with your doctor before engaging in more vigorous exercise.