Interval Walking Training · on your wrist
A walking coach you feel, not watch.
StepFlow taps out the Japanese 3-and-3 protocol from your watch: three minutes brisk, three minutes easy, five times. Distinct haptics for every switch, so your eyes stay up and your phone stays home.
Free during beta · Apple Watch first, Wear OS in development
The method
Thirty minutes. One rule. Decades of evidence.
Interval Walking Training was developed by Prof. Hiroshi Nose and Dr. Shizue Masuki at Shinshu University in Japan: walk fast enough that talking is hard for three minutes, then stroll for three, and repeat five times. In the landmark trial it beat steady walking at the same total effort, decisively.
knee-extension strength after 5 months
peak aerobic capacity (VO₂ peak)
adherence in adults with a mean age of 63
Nemoto et al., Mayo Clinic Proceedings, 2007 · 246 participants, 5 months · all references
Haptic-first
You'll feel it before you'd need to look.
Every timer app can buzz when a block ends. StepFlow counts you in: three rising taps before each switch, so the change of pace never ambushes you mid-stride. Five cues, each distinguishable blind, mid-walk, with the screen off and your wrist down.
- Countdown 3 · 2 · 1 before every switchthree ascending taps
- Go push the brisk block startsstrong double knock
- Ease down the recovery block startsone soft, long roll
- Block complete a block endssingle tap
- Session complete all five reps donea little flourish
Cues fire reliably with the display off because the workout session keeps the app alive. Listening to something? Audio cues duck your music and podcasts, they never cut them off. Silent mode falls back to haptics alone.
HR-validated intensity
Your 70% isn't a guess.
"Brisk" means about 70% of your heart-rate reserve; easy means about 40%. StepFlow computes both from your resting and max heart rate (the Karvonen method), not the 220-minus-age formula that misses real people by 10 bpm or more. No measured max? A talk-test helper gets you close.
- Push · Z3 Fast enough that full sentences get hard.
- Ease · Z1 Comfortable enough to chat while your heart resets.
- Patient nudges Off pace? One gentle tap, only after 25 seconds out of zone. Your heart rate lags at every switch; StepFlow knows that and never nags while you're getting there.
Private by design
Built like a tool, not a funnel.
No phone on the walk
StepFlow is a standalone watch app. Start from your wrist, walk, come home. The phone can stay on the counter.
No account. No cloud.
Nothing to sign up for and nothing to upload. Sessions and heart-rate data stay on your watch, in Apple Health or Health Connect, under your control.
No ads, no analytics
No third-party trackers, no data brokers, no "anonymized insights." Your walk is yours.
Questions
Frequently asked questions
What is StepFlow?
A wrist-native coach for Interval Walking Training. It runs the 3-minutes-brisk / 3-minutes-easy protocol from your watch with distinct haptic cues for every transition, plus live heart-rate zones tuned to you.
What is Interval Walking Training?
A walking protocol developed at Shinshu University in Japan: alternate three minutes of brisk walking with three minutes of easy walking, five times, about 30 minutes total. In a 5-month trial it improved leg strength, aerobic capacity, and blood pressure significantly more than steady moderate walking.
Do I need my phone?
No. StepFlow is fully standalone: start the session from your watch, and everything runs on the watch. There is no companion app to install.
Which devices are supported?
Apple Watch first (watchOS 11 and later). A Wear OS version is in active development and beta testers will get it first.
How are my heart-rate zones set?
From your resting and maximum heart rate using the Karvonen (heart-rate-reserve) method: the brisk target is about 70% of your reserve, easy about 40%. If you have never measured a max, a built-in talk-test helper gets you a working estimate. StepFlow never uses the 220-minus-age formula.
Will it interrupt my music or podcasts?
No. Audio cues briefly duck what you are listening to and then bring the volume right back. With the watch in silent mode, StepFlow falls back to haptics only.
I'm not athletic. Is this for me?
Especially for you. The protocol was designed for and studied in ordinary adults, most in their 50s, 60s and 70s. It is low impact, needs no equipment, and 95% of trial participants were still doing it at the end of five months.
Is it free?
Free while in beta. The plan is a one-time purchase, never a subscription, and never ads.
Who developed the method?
Prof. Hiroshi Nose and Dr. Shizue Masuki at Shinshu University Graduate School of Medicine, whose team has published on IWT for two decades. See the references page for the papers.
Be walking by spring.
Beta invites go out in small waves, Apple Watch first. One email when your spot opens, nothing else.
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