What it does
Underdog turns Apple Watch heart rate data into a training game. Time in each heart rate zone earns points - Zone 2 work is rewarded - and you compete in weekly leagues with friends, climbing from Bronze to Diamond.
Why it helps
Zone training only works if you actually stay in the zone. Underdog tracks it automatically during any workout and turns consistency into a competition, which makes easy-pace discipline much easier to keep.
Key details
- Automatic heart rate zone tracking on Apple Watch
- Weekly leagues: Bronze to Diamond
- Free on iPhone
