Privacy Policy
Last updated: 9 September 2026
Yield Strength is a strength-training app with an AI coach, made by Northline Standard LLC ("we", "us"). This policy explains what data the app collects, why, who else sees it, and how to get rid of it. It covers the Yield Strength iOS app and this website.
The short version. We collect the training you log, the profile you tell us about, and — only if you allow it — recovery and body data from Apple Health. We use it to coach you. We share it with a small number of service providers who help run the app, including an AI provider that generates the coaching text. We do not use it for advertising. You can delete your account and everything in it from inside the app at any time.
What we collect
Account information
When you sign in we store your email address and an account identifier. If you use Sign in with Apple and choose to hide your email, we only ever receive Apple's private relay address, not your real one. We never see or store a password — sign-in is either a one-time code sent to your email or Sign in with Apple.
Training data
The substance of the app: workouts and the sets inside them (exercise, weight, reps, and reps-in-reserve where you record it), training blocks and their weekly targets, personal records, the progression recommendations you were shown and whether you accepted or overrode them, session scores, and any notes or workout names.
Profile and equipment
What you tell us about yourself so the coaching is calibrated: your training goal, how long you've been training, body weight, how many days a week you train, and the equipment you have access to. All of it is optional.
Apple Health data — only with your permission
If you grant Health access, Yield Strength reads the following so the coach can account for how recovered you are:
- Sleep analysis
- Heart rate variability (SDNN) and resting heart rate
- Body mass and body fat percentage
- VO2 max and Apple exercise time
- Dietary energy, protein, carbohydrate and total fat
- Blood pressure (systolic and diastolic), on operating system versions that support it
Yield Strength never writes anything back to Apple Health — the app requests read access only. Health access is entirely optional, the app works fully without it, and you can switch it off at any time under Profile → Apple Health or revoke it in Apple's Health app. We never sell Health data, and we never use it for advertising.
Conversations with the coach
What you say to the coach and what it says back, so the conversation persists and the coaching stays consistent with your training.
Usage analytics
To build the best app we can, we pay close attention to how Yield Strength is actually used — both in the app and on this website. We record what you do and how you move through it: the screens and pages you visit, what you tap and click, the paths you take, how often and how long you use it, where you came from, and your device and rough location (derived from your IP address). This includes session replays and heatmaps — a reconstruction of how the app's own screens and pages were tapped, scrolled and moved through, so we can see where something trips people up. Anything you type into a field, such as your email, is masked out. On the website this covers visitors before they ever sign in.
What this never includes is the substance of your training. We deliberately do not send your exercise names, weights, reps, health readings, or any of your conversation with the coach to our analytics — that stays in your own account. Once you're signed in, your usage is linked to you, so we can understand real behaviour over time rather than anonymous fragments. We use all of it for one thing: to understand what's working, fix what isn't, and make Yield Strength better.
Crash diagnostics
If the app crashes, it records what went wrong so we can fix it — the technical details of the failure (the type of crash and the sequence of code that led to it), plus your app version, iOS version and device model. That report is saved on your device and sent the next time you open the app. A crash report contains no training data, no health readings and no part of your conversation with the coach. It is linked to your account identifier so we can tell how many people a given crash affected and follow up if you asked us to.
Errors the app handles on its own — a sync that failed and will retry, a coach reply that timed out — are not reported as crashes.
Who else sees your data
We use a small number of service providers to run Yield Strength. They process data on our behalf, under their own terms, and are not permitted to use it for their own purposes.
| Provider | What they receive | Why |
|---|---|---|
| Supabase | Account, training data, profile, equipment, coach conversations, and Health-derived recovery snapshots if Health is enabled | Database, authentication and sync, so your training survives losing your phone and follows you across devices. Hosted in the United States. |
| Anthropic | Your coach conversations, a summary of your recent training and profile, and — when Health is enabled — your latest recovery and body measurements | Generating the coaching text and workout plans. This is how the AI coach works; there is no on-device alternative. |
| PostHog | Usage and traffic analytics from the app and website, session replays and heatmaps, crash diagnostics, and your account identifier and email — no training content, health data, or conversation text | Product and website analytics, session replay, and crash reporting. Hosted in the United States. |
| Apple | Purchase and subscription information | App distribution and payments. Apple processes any payment; we never see or store your card details. |
We may also disclose data if we are legally required to, or to protect our rights or someone's safety. If Northline Standard is ever sold or merged, data may transfer as part of that — you'd be told before it happened.
Where your data is stored
Your training is stored on your device and, when you're signed in, synced to our servers in the United States. If you're outside the US, using Yield Strength means your data is transferred there.
Deleting your account and your data
You can delete your account from inside the app: Profile → Delete Account. It asks you to confirm, and then it is permanent — we cannot recover it for you afterwards.
Deleting your account removes, from our servers:
- Every workout, set and session you've logged
- Your training blocks and their weekly plans
- Your personal records and progression history
- Your profile and equipment settings
- Recovery and body measurements read from Apple Health
- Any exercises you created yourself
- Your account itself
One thing we keep. Yield Strength's coach shows a notice that its guidance is coaching, not medical advice, and asks you to acknowledge it. We retain the record of that acknowledgment — that an account with your email address agreed, when, and to which version of the wording — even after the account is deleted. We keep it as evidence that the disclosure was made and accepted, which we have a legitimate interest in being able to demonstrate. It contains no training data, no health data, and no conversation content.
Deleting your account does not cancel an App Store subscription — only Apple can do that. Cancel it in Settings → your name → Subscriptions on your device, or you will continue to be charged.
How long we keep things
We keep your training data for as long as you have an account, because the whole point is to compare what you're lifting now against your own history. Delete your account and it goes, apart from the acknowledgment record described above. Analytics events are retained by our analytics provider under their retention settings.
Your choices
- Apple Health: optional, off until you allow it, and revocable at any time in the app or in Apple's Health app.
- Deletion: available in the app, no need to contact us.
- Access and correction: most of your data is visible in the app, and your profile and logged sets are editable there. For anything else, write to us.
- Analytics: Yield Strength does not currently offer a separate opt-out from usage analytics. If that matters to you, contact us and we'll handle it manually.
Depending on where you live you may have additional rights over your personal data. Write to us at the address below and we'll do what's required.
Security
Data is encrypted in transit. Your sign-in session is held in the iOS Keychain. On our servers, access rules are enforced per account, so one lifter's data is not readable by another. No system is perfectly secure, and we don't claim otherwise — but we keep the most sensitive things you trust us with, your training, your health readings and your conversations with the coach, out of our analytics entirely, which is the most reliable protection available.
Children
Yield Strength is not intended for anyone under 16, and we don't knowingly collect data from them. If you believe a child has created an account, contact us and we'll remove it.
Not medical advice
Yield Strength's coaching is training guidance, not medical advice, and it is not a substitute for a physician or other qualified professional. Lifting carries risk. Talk to a doctor before starting or changing a training programme, especially if you have an injury or a medical condition.
Changes to this policy
We may update this policy as Yield Strength grows and changes. When we do, we'll change the date at the top, and the version you're reading is always the one that applies — continuing to use Yield Strength means you're going along with it. If anything here ever raises a question for you, we'd genuinely rather hear about it than have you wonder.
Contact us
Privacy questions, requests, or anything in this policy that reads wrong to you:
yieldstrength-support@northlinestandard.com
Northline Standard LLC, Utah, United States