Cardio Fitness + Widgets allows you to track your cardio fitness.
Cardio fitness is a measurement of your VO2 max, which is the maximum amount of oxygen your body can consume during exercise. Your cardio fitness level is a strong indicator of your overall physical health and a predictor of your long-term health.
VO2 readings from your Apple Watch, those manually logged in the Health app or a third party app will be available in the app, home screen and lock screen widgets. This is very convenient for pro athletes or anyone who wishes to monitor their health goals.