Pro Training. Max Results.
A focused HIIT interval trainer for iPhone and Apple Watch that helps you raise your VO₂ max — the single best number for long-term fitness.
Coming soon to the App StoreNorwegian 4×4, true Tabata sprints, and 30/60 intervals — science-backed sessions with guided warm-up and cool-down.
Your Apple Watch streams live heart rate into every workout with real-time zone targets: keep pushing, hold it, or slow down.
See your estimated VO₂ max from Apple Health and a projection of where ~8 weeks of training can take it.
Build your own intervals — rounds, push, and recovery — and keep them in your personal library.
Train smarter and see where it takes you.