Whistle is an AI workout planner built for runners, cyclists, swimmers, and triathletes who want more than a generic training plan. It helps you plan, adapt, and understand your training built around your body, your schedule, and your goals.

The app connects to Apple Health to pull in your workouts, sleep, recovery, and heart rate data, then uses that context to give you coaching that actually reflects how you are doing. Before you head out the door, you can see how ready your body is, how a workout is likely to feel, and what the weather looks like for your planned session. Your coach can plan your week, adjust workouts on the fly, review your progress, and send daily summaries that connect your training, recovery, and upcoming day.

Whistle 2026.1 is the biggest update since launch. Training programs are now built into a dedicated Plan tab, where you can start a guided setup, build a longer program with your coach, or bring an existing plan into the app. The AI coach has been rebuilt from the ground up and is now more capable across everyday planning, with support for voice and photos, richer context, and daily summaries. The improved dashboard brings training load, recovery, sleep, vitals, weather, and planned workouts together in one place. Workout planning got more precise too, with targets for single-goal workouts and smarter estimates overall.

Whistle is built by us, Flo and Clemens, with the goal of building the fitness app of our dreams. If you try the app we would be happy to hear your thoughts, so feel free to send us an email any time.