ZoneSprint

ZoneSprint is a mobile app (iOS/Android) that runs HIIT and cardio sessions using real-time heart-rate zones from Apple Watch, Wear OS, or common BLE straps. Instead of fixed timers, intervals extend or shorten to keep you in the target zone (e.g., 85–92% max HR) and back off when you’re overcooked. It’s built for people who train inconsistently, get gassed early, or plateau because they’re guessing intensity. Workouts are short (8–25 minutes), equipment-optional, and include running, cycling, rowing, and bodyweight options. The app learns your recovery rate and adjusts future sessions, then gives a simple weekly “readiness vs. intensity” plan so you don’t overtrain. It’s not a full coaching platform; it’s a tight, measurable loop: hit the zone, recover, progress, repeat.