The 30-day BP reset · iPhone
Your blood pressure is in the gray zone.
You have 30 days.
Not sick enough for aggressive treatment. Not healthy enough to ignore it. UNDERPRESSURE is the structured protocol that was missing: nineteen ranked levers across four weekly phases, scored on your readings — and nothing ever leaves your phone.
Free to log · Pro 7-day trial · iOS 17+ · No account, ever
The gray zone
You've been told to "watch it." Watching is not a plan. Between 120/80 and the day someone writes a prescription there is a window — and the healthcare system has no protocol for it. This is one.
The protocol
Four weeks. Nineteen levers. Introduced in phases, so the rankings can tell them apart.
Everything lands at once and you learn nothing. UNDERPRESSURE staggers the stack so that by week three the app can see which levers moved your numbers — and by week four you know which one to double down on.
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WEEK01
Install
Foundation. Days 1–7. Baseline your readings, install the habits with the biggest effect sizes.
- Wall sits
- Zone 2 cardio
- Box breathing
- Sodium restriction
- Beetroot juice
- Alcohol elimination
- Magnesium glycinate
- Omega-3
- Vitamin D3 + K2
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WEEK02
Deepen
Stack expansion. Days 8–14. Heat, deliberate rest, and the second supplement tier.
- Sauna
- NSDR
- CoQ10
- L-citrulline
- Aged garlic
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WEEK03
Load
Full stack. Days 15–21. Easy running returns and the lever rankings reach moderate confidence.
- Easy running
- Low-dose melatonin
- Berberine
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WEEK04
Compound
Optimization. Days 22–30. Find your weakest lever, then run the final seven-day benchmark against your baseline.
- Resistance training
- Cold plunge
Today's protocol · personalized at onboarding
The app
Built to be read at 7 a.m. with one eye open.
Your reading fills the screen. Red means high, teal means in range, amber means take it easy — color always means something. No streaks, no badges, no confetti. The only celebration is a lower number.
01 · The ritual
Fifteen seconds, every morning.
One check-in a day: your reading, your context, your protocol items. Manual entry is first-class — three wheel pickers, done. If your cuff wrote a reading to Apple Health, it's already filled in.
- Context that matters to athletes — sleep, training load (TSS), sodium, alcohol, stress. All optional, all correlated later.
- Apple Health, read-only — Withings, Omron, QardioArm and any cuff that syncs to Health.
- Crisis guidance built in — a reading of 180/120 or higher stops the flow and tells you what to do.
02 · Lever rankings
See what actually works — for you, not the average.
From day 7, every lever gets a score: your mean systolic on the days you did it versus the days you didn't. It's a pattern in one person's data — the app is upfront about that — but the person is you, and the picture gets sharper every week.
- Confidence that grows with data — low at day 7, moderate at 14, full at 21.
- Correlations on the dashboard — alcohol, stress, sleep and training load against your systolic.
- Week-four insight — the weakest lever gets named so you know what to cut or fix.
03 · Timer & breathwork
The two levers with the best evidence, built in.
Isometric training is the exercise mode with the largest blood-pressure reductions in the 2023 BJSM network meta-analysis. UNDERPRESSURE ships the timer for it: four two-minute wall sits with haptic cues, so you never look at the screen.
- Haptics, not glances — pulse on inhale, double-pulse on exhale, triple-tap when a set is done.
- Four guided breaths — box breathing, extended exhale, the physiological sigh, and NSDR.
- Pauses when you leave — background the app mid-set and it waits for you.
Home-screen widget
Your latest reading, its time, and a nudge when it's more than a day old.
Trends that respect the noise
7- and 30-day views free; 90-day for Pro. Systolic and diastolic on one chart, MAP computed for you.
Personalized at onboarding
Don't drink? No alcohol lever. On medication? Interaction-prone items are held. Your baseline, your stack.
Dark, always
Every reading you take is at 7 am in low light or at 9 pm before bed. The app is built for that room.
The evidence
Every lever traces back to a named study.
Not a wellness blog's list of tips. Meta-analyses and large cohorts, cited in the app next to each lever. Here are the ones doing the heavy lifting.
Isometric exercise produced the largest resting BP reductions of any training mode.
Network meta-analysis of 270 randomized trials, 15,827 participants. Wall squats were the single most effective protocol studied.
Edwards et al., Br J Sports Med 2023 Sauna 4–7×per weekFrequent sauna bathing was associated with markedly lower cardiovascular and all-cause mortality.
The Kuopio Ischaemic Heart Disease cohort: 2,315 middle-aged men followed for a median of 20 years.
Laukkanen et al., JAMA Intern Med 2015 Breathing · physiological sigh 5 mindailyFive minutes of structured breathing a day outperformed mindfulness meditation for mood and physiological arousal.
Randomized controlled study; cyclic sighing produced the largest improvements and lowered resting respiratory rate over a month.
Balban et al., Cell Reports Medicine 2023 Sodium Dose–responselinearBlood pressure falls in proportion to how much sodium you cut — with the steepest slope in people who already run high.
Meta-analysis of 85 randomized trials. The relationship held across the full range of intakes studied.
Filippini et al., Circulation 2021 Magnesium 34 RCTsn = 2,028Magnesium supplementation lowered systolic and diastolic pressure in randomized trials.
Effects were modest on average and larger with longer supplementation; the app pairs it with sleep, where it earns its keep twice.
Zhang et al., Hypertension 2016 Omega-3 70 RCTsEPA + DHALong-chain omega-3s reduced blood pressure, with the largest effect in untreated hypertensive participants.
Meta-analysis of randomized trials; effect size scaled with dose.
Miller et al., Am J Hypertens 2014 Beetroot · dietary nitrate Nitrate → NOmechanismInorganic nitrate from beetroot juice lowered systolic pressure across randomized trials.
Nitrate becomes nitric oxide, which relaxes the vessel wall — the same pathway L-citrulline feeds from the other side.
Bahadoran et al., Crit Rev Food Sci Nutr 2017 Thresholds 130/80Stage 1The 2017 ACC/AHA guideline that redrew the lines — and put millions of people who train into the gray zone.
Its first-line recommendation for Stage 1 without high cardiovascular risk is lifestyle intervention, re-assessed in three to six months. That is this app.
Whelton et al., Hypertension 2018Not medical advice. UNDERPRESSURE is a wellness app, not a medical device. It does not diagnose, treat or prevent any condition. Talk to your physician before starting the protocol — especially if you take any medication — and never change a prescribed medication because of a number in the app. Supplement items are a reference stack drawn from the literature above; whether they are right for you is a question for your doctor.
Privacy
Your readings never leave your iPhone. Not encrypted-in-transit. Not anonymized. Never sent.
There is no UNDERPRESSURE account and no UNDERPRESSURE server. Your readings live inside the app, on your phone. Apple Health is read-only. There is no analytics, no crash reporting, no advertising identifier and no third-party code inside the app — which is why the App Store privacy label can say what most health apps can't.
Data Not Collected
Delete the app and every reading, answer and preference goes with it. Because nothing is stored on our side, there is nothing for us to hand to anyone else. Read the full policy →
What it costs
Logging is free. The protocol is Pro.
Seven days free to run week one and see whether the ritual sticks. Cancel in one tap; your data stays either way.
Free
- Blood pressure logging with MAP and category
- 7- and 30-day trends
- Reading history, delete anything
- Home-screen widget
- Apple Health import
Everything above stays free when a Pro subscription ends.
Pro
or $79.99 / year · save 33%
- The full 30-day protocol engine, four phases
- Daily action items, personalized to you
- Lever efficacy rankings from day 7
- Correlation analysis on your context
- 90-day trends
- Isometric timer with haptics
- Guided breathing: box, exhale, sigh, NSDR
- Reference supplement stack, gated by your answers
Auto-renews through your Apple Account. Stop mid-protocol and it pauses on that day; come back and it resumes.
Questions
Straight answers.
Does this replace my doctor?
No. It's a wellness app, not a medical device. Stage 2 readings route you to a physician, not to the protocol, and a reading of 180/120 or higher triggers emergency guidance on screen. The right way to use it is with your doctor: run the protocol, bring the trends to your next appointment.
I take blood pressure medication. Can I use it?
Yes — with your physician's okay. Tell the app during onboarding: interaction-prone items such as berberine are held back, and the app never suggests changing a prescribed medication. Keep taking what you were prescribed.
Where does my data go?
Nowhere. Readings, answers and rankings live in the app's database on your iPhone. There's no account, no server, no analytics and no third-party code. The App Store privacy label is "Data Not Collected". Deleting the app deletes everything.
Do I need a blood pressure cuff?
Yes — any validated upper-arm cuff. If it syncs to Apple Health (Withings, Omron, QardioArm and others) the reading pre-fills your check-in. If it doesn't, you type it in with three wheel pickers. It takes fifteen seconds either way.
What if I miss a day?
Nothing punishes you. There are no streaks, badges or confetti anywhere in the app. The lever rankings simply have one fewer day of data.
Why is it built for athletes?
Because endurance athletes and strength athletes with elevated pressure get told to "take it easy" by people who don't train. The protocol keeps you training — Zone 2, isometrics, easy running, resistance work are levers, not sacrifices — and it logs training load next to your readings so you can see what a hard week actually does to your numbers.
What happens after 30 days?
You get a final seven-day benchmark against your baseline and your complete lever rankings. Run another reset, or keep logging for free. Your history stays.
Can I cancel anytime?
Yes, in your Apple Account subscriptions, in one tap. If you stop mid-protocol it pauses on that day and resumes where you left off when you return. Logging, trends and history stay free.
Why iPhone only?
Because we built it properly for one platform first: Apple Health, the home-screen widget, everything stored on the phone. Android isn't planned for this version.
If you've read this far,
the window is still open.
Thirty days. One check-in a morning. A ranked answer to the only question that matters: what actually moves your number.
30 days · 19 levers · 0 streaks · 0 servers