Features
Five protocols. One coach. Everything it takes to run both well.
Five named, research-backed protocols
Zone 2 for open-ended steady-state work. Norwegian 4x4 — four minutes hard, three minutes easy, four rounds. 12-3-30 — 12% incline, 3 mph, 30 minutes, no heart rate monitor needed. Tabata — 20 seconds on, 10 seconds off, eight rounds. Wim Hof — guided breathing rounds with a breath-hold timer. Each one gets its own screen explaining what it is and why, plus a "just start" path once you know it.
Real-time voice coaching
For the heart-rate-based protocols, Cardio Protocol speaks up when you drift out of zone — "above zone, ease off," "in zone," "below zone, push" — spoken at sensible moments (a zone transition, plus a periodic check-in), never a constant stream of noise.
A full Apple Watch companion app
Start and stop a session independently from your wrist. Your current phase, live heart rate, and zone status are all live on the watch face, and mirrored to your iPhone's Lock Screen and Dynamic Island via Live Activities.
Heart rate from Health or a chest strap
Reads live heart rate through Apple Health via your Apple Watch, or connects directly to a Bluetooth chest strap for lower-lag readings if you have one.
History that actually explains your session
Every saved session shows total time, calories, average/min/max heart rate, a full heart rate trend chart, a computed time-in-zone breakdown, a per-phase breakdown, and your heart rate recovery after the last hard interval — plus space for your own notes and a 1–10 effort rating.
Only asks about the sessions worth keeping
A session under a minute is skipped automatically — that's not a real workout, it's a mis-tap. Right on the edge, the app asks whether to save it or let it go, instead of quietly guessing either way. Any saved session can be deleted from its detail screen whenever you want.
Data export & optional iCloud backup
Export your full session history as a single file whenever you want a personal backup, or turn on automatic iCloud backup so your history follows you across devices — entirely within your own iCloud account.
No social feed. No leaderboard. No ads.
Cardio Protocol is built to be used, not scrolled. No feed to compare yourself against, no ads interrupting a session, nothing competing for your attention beyond the protocol itself.