The data your watch already collects
If you wear an Apple Watch, Garmin, Whoop, Oura, Fitbit or any Android wearable, your device is already collecting four metrics every night that — together — tell us almost everything we need to know about whether you’re ready to train hard tomorrow:
- Sleep duration and stages. How long you slept, how much of it was deep, how disturbed the night was.
- Heart rate variability (HRV). The single best predictor we have of autonomic nervous system recovery. Higher overnight HRV = more recovered.
- Resting heart rate (RHR). Trending up over a few nights = stress, illness, overtraining, or a combination.
- Yesterday’s strain. How hard the previous day worked your cardiovascular system.
Most apps display these as line charts you can scroll through in the morning if you remember to look. Few apps actually do anything with them.
What we do with it
Every morning at 6am local time, the MyPT app reads these four signals and computes a single colour: green, amber, or red. We use this signal to change today’s training plan before you open the app.
- Green = recovered. Today’s plan runs as written. If you wake up feeling springy, optional bonus volume is unlocked.
- Amber = partially recovered. The HIIT block becomes a Zone-2 walk. The 5×5 squat becomes 5×5 at 80% of last week’s load. The plan still moves forward, just gentler.
- Red = not recovered. The session becomes mobility, breathwork, and a recovery walk. We encourage you to take it seriously rather than grind through.
By the time you check your phone in the morning, today’s plan already reflects how you slept. This is the part new clients find genuinely surprising — the realisation that a coaching tool can adapt to the body that woke up, not just the plan that was written.
Why this matters more than people think
The reason most training plans fail isn’t bad programming. It’s that the programming was written for a “version of you” that doesn’t exist on any given day. Real you on a Tuesday after three nights of poor sleep is not the same as theoretical-you the programme assumed.
If you train hard on red days, three things happen:
- You don’t get the adaptation you wanted (your body has no spare resources to build with)
- You dig the recovery debt deeper (it takes longer to come back next session)
- You teach your brain that training feels bad (motivation collapses over weeks)
If you train gentle on green days, you leave gains on the table that you could have made for free.
The readiness signal isn’t an excuse to skip sessions. It’s a tool to work hard on the right days and recover on the wrong ones. Over a year, this changes the trajectory of progress more than any other single coaching decision.
What “HRV” actually is, briefly
If you’ve never had it explained: HRV is the millisecond-level variation in time between your heart beats. Not heart RATE (beats per minute) — heart-rate VARIABILITY (the tiny gaps between beats).
A healthy autonomic nervous system shows MORE variability because it’s flexibly responding to your body’s needs moment-to-moment. A stressed, fatigued, or sick autonomic nervous system shows LESS variability — the rhythm becomes more metronomic.
We measure overnight because daytime HRV is contaminated by everything you’re doing (coffee, conversations, traffic). Overnight HRV is the cleanest baseline reading we get.
Trend matters more than any single reading. A 50ms HRV that drops to 35ms over four nights is more meaningful than a 50ms reading that drops to 40ms once.
Which wearables we support
The MyPT app pulls data from:
- Apple Watch via HealthKit (iOS)
- Health Connect on Android (Galaxy Watch, Pixel Watch, Mi Band, anything that writes to Health Connect)
- Fitbit (Charge, Sense, Versa)
- Garmin (Forerunner, Fenix, Venu, Vivoactive, Edge)
- Whoop
- Oura Ring
If you have one of these, the connection is one-tap OAuth from inside the app. Background sync runs from then on. If you have multiple wearables (some clients run Whoop + Garmin), we pick the more reliable signal per metric and combine them.
What if you don’t have a wearable
The full coaching works without one. Manual entries let you log heart rate, sleep duration, and resting heart rate — the readiness signal still computes from manual data, just less richly.
A wearable makes the readiness signal richer and less effortful. It’s not required.
The single biggest “why did nobody tell me this” moment
When a new client gets their first amber-day plan-swap from the app — they often message us. The realisation that a “fitness app” can ACT on the data instead of just displaying it changes how they see the whole training enterprise. The science behind this isn’t new. The implementation is what’s been missing.
Most apps still treat your watch as a passive sensor. We treat yours as a co-coach. The plan that wakes up with you is the plan that actually fits the body that woke up.