Apple Watch workouts fall into two categories:
- Some workouts, like "Outdoor Run" are optimized to the specific workout. This means they understand what your whole body is doing and are tuned to use just your wrist movement/heart rate to understand the intensity of the workout.
- Other workouts, like "Other" are not tailored to any specific workout. This includes some labeled workouts, which work like "Other" but label the workout appropriately. Football falls into this category, it's using the "Other" algorithm under the hood.
You can read more about this from this support article - the ones that do not have their own section in this article fall into "Other": https://support.apple.com/en-us/HT207934
When you use Other, or any workout type available in the Add Workout section, you earn the credit equivalent of a brisk walk when these sensor readings are unavailable.
This means that your results can be inflated if the watch is having trouble understanding what you're doing, as it defaults to "brisk walk" in those scenarios.