The Running Training App That Explains Your Pace.
Connect your watch and your whole history is in within minutes. From there, OSO reads every run back to you in plain English and tells you what to train next. Every number traced to a run you actually did, none of it guessed by a chatbot.
Every Run, Read Back in Plain English
Upload a run and OSO works through the effort behind the pace, hills and all, then hands you the verdict in a sentence you can act on. Not a wall of charts to interpret yourself, and not a chatbot improvising.
- A plain-English read of the runWhat the effort built, and what to watch as you recover.
- Grade-adjusted paceSo a hilly run and a flat one finally compare.
- Pace zones off your own thresholdNot a population table.
The Engine Behind Your Pace
OSO fits a critical speed model to your own best efforts, so every zone comes from your running rather than a formula, then names the one system holding you back and the session that trains it.
- Critical speed and threshold paceStraight from your fastest sustained efforts.
- Your limiter, namedThe gap against your own curve, and one tap to train it.
- Race predictions5K to the marathon, projected from your own bests.
Know Whether to Go Hard Today
Every run feeds one fitness, fatigue and form curve, so whether you are fresh enough to hit a hard session is something you can see, not a feeling you second-guess.
- Fitness and formIn one chart you can read at a glance.
- Health and recoveryHRV, resting heart rate and sleep, next to the training that moved them.
- A layout you arrangeAround the numbers you actually check.
Plain English, Not an AI Guess
After every session, OSO explains in plain language how hard it really was and what it did to your engine, then tells you where to take the next one. That read is not a language model improvising, and the difference runs deeper than the words.
An AI coach builds each answer from scratch, and the models behind it drift. They are retrained and reweighted over time, so one session can earn a different verdict next month, with nothing to tell you what changed or why. OSO has nowhere to wander. It works from a defined set of inputs, your own recorded pace efforts, through a fixed, finite set of conclusions, each one designed and named in advance and grounded in published, cited sports science. The same session reads the same way today and a year from now. OSO names the evidence behind every claim, and stays silent rather than reach for one your data cannot support.
Looking for a Running Training Plan?
OSO gives you structured training plans, just never one written for somebody else. A plan here scales its sessions to your own threshold pace and heart rate, and reads from all of your numbers rather than a single test, so it adapts as your engine and your week change. We still believe in the human element of sport. There is no AI chatbot here spitting out your workouts, and any athlete who wants a lot of hands-on direction we point to a qualified coach.
Underneath every plan, OSO models your engine from your own pace and heart rate data, tells you what each session cost and what it built, and gives you a builder and a calendar to reshape the block whenever you want. You decide the shape of the week. OSO makes sure the numbers underneath it are yours.
If you already follow a plan from a coach, that works too. Build the sessions, send them to your watch, and use OSO to check that the block is landing the way it was drawn.
Common Questions
Is OSO a running training app?
Yes. OSO is a running training app (equally at home called a running training platform) built around one idea: every number is computed from your own recorded efforts, never from population tables. It runs in the browser, connects to Strava, Garmin, Wahoo, Polar and Hammerhead, and the essentials are free.
How does OSO work out my threshold pace?
From your own best efforts across every duration rather than from a formula. As your fastest sustained paces improve, your threshold and every zone built on it move with them.
Does OSO handle both running and cycling?
Yes, and that is the point. Rides, runs and swims land in one training picture, so a hard week on the bike shows up in the fatigue you carry into a run. Zones stay sport specific: running is scored on pace, not on a cycling threshold.
Can I send sessions to my watch?
Yes. Build a structured session in OSO and push it to your Garmin or Wahoo watch. OSO sends the steps and pace targets, then reads the session back to check what the device actually kept, and tells you if anything was simplified on the way.
Does it work with Strava?
Yes. Connect Strava or Garmin and your history imports automatically. You can also upload FIT files directly.
What does it cost?
OSO's essentials are free, with an optional Premium plan at $9.99/month. Your training history exports whenever you want it.