The Apple Watch Now Has Training Load

Apple also introduced something new called Training Load. This is a feature that will keep track of your workouts in a different way.
Training Load will track the intensity and duration of your workouts. It’ll also use your heart rate, pace, and other personal data, such as your weight, height, and age, to determine the impact of your workouts on your body.
Depending on how much you’re pushing yourself, you’ll see a score that goes from one to ten. This effort will be calculated automatically, but if you feel like your effort was greater, you can manually change the level yourself.