Features
Compatible with
Your Whole Season on One Screen
- One model, every sportRide, run and swim feed a single fitness, fatigue and form curve, planned sessions forecast forward.
- Health and recoveryHRV, resting heart rate and sleep, read against the training that moved them.
- A dashboard you arrangePlain-English insights call out what is driving your form now.
- Yours to keepExport your full history anytime. The essentials stay free.
Every Session, Read Closely
- A plain-English readHow hard the session was for you, and what it built.
- Zoomable streamsPower, heart rate, pace and cadence, with a map cursor that tracks your scrub.
- Sport-correct zonesRuns scored on your pace, rides on your power.
- Durability and decouplingHow your second half held up against your first.
A Model of You
- Critical power and W′Fit to your own best efforts and updated as you train. Critical speed for runners.
- Your limiter, namedThe energy system furthest behind, with a one-tap session to close it.
- Personal recordsEvery duration, kept current from every upload.
Build the Session, Keep What Works
- Every step type, in any orderWarmups, intervals, ramps and recoveries, dragged where you want them.
- Targets from your own zones%FTP, watts, pace or heart rate, switched across the session in one tap.
- Save the workout or one blockStart from a template, reuse what worked in the next build.
- Preview, notes and fuelingThen send it straight to your head unit.
Lay Out the Weeks, Not Just the Day
- A weeks-by-days gridDuration and Effort add up as you fill it.
- From your own workouts, never cannedFill a cell from your library, or build one in place that lands in the plan and library at once.
- Rest that counts as restMark a day recovery and the plan reads it as rest.
- Apply the whole blockPick a start date and every session lands on your calendar, feeding the fitness and form forecast.
No Population Tables
Every threshold, zone and grade in OSO is computed from your data against your physiology. If a number cannot be traced back to something you actually did, we do not show it.
Not an AI Coach
Every number is computed, not generated. A language model predicts words. It does not measure watts. Everything OSO tells you is calculated from your own efforts against a named physiological model, so the read is about you and nobody else.
You can check the math. Every claim traces back to a specific model, from Critical Power to the Banister impulse-response model, all cited on the Training Science page. Don't take our word for it. Go look.
When the data is thin, OSO shuts up. Plenty of apps will hand you a confident number built on three rides. We won't. If your data can't support a conclusion, you get silence instead of a guess.