Training science,
made legible.

Why we built it

Serious endurance athletes end up assembling their own toolkit — a training platform here, a recovery app there, and a spreadsheet holding it all together. Each one hands over a score. Almost none of them explain where it came from, and fewer still let you disagree with it.

We thought the athlete who trains with intent deserved better than a black box. So Meridian does the hard part — reading your readiness, budgeting your training load, building the session, planning the fuel — and then shows its work. Every figure has a formula behind it. Every threshold can be tuned. Nothing is hidden behind a friendly number.

How Meridian thinks

Each morning, Meridian reads the signals your body already gives you through Apple Health — heart-rate variability, resting heart rate, sleep, and energy — and turns them into a readiness score. It weighs that against your recent training load and how much room you have left before pushing harder stops paying off.

From there it builds the day: an easy session when you need one, a hard one when you've earned it, sized to a specific training-load budget rather than pulled from a template. Then it sends that workout to your Apple Watch, guides your fueling around it, and folds the result back into the picture it's building of you.

Meridian was created with care, based on the latest in training and conditioning science — established models for training load, workload ratios, heart-rate zones, and fitness trajectory, implemented faithfully rather than approximated.

What we believe

• Transparency over trust-me. If we can't explain a number, we shouldn't show it.
• The athlete is in charge. Our model is a starting point, not an authority. Tune it.
• Privacy is architecture, not policy. Meridian runs on your device. There's no account, and we don't collect your health data.
• Performance, not diagnosis. Meridian is a training and wellness tool. It doesn't diagnose or treat anything, and it never pretends to.

Available on iOS

Meridian is built for iPhone and Apple Watch and integrates deeply with Apple Health. It is an iOS-only app at this time. That may change in the future, but we'd rather do one platform properly than several of them halfway.

The company

Meridian is made by Meridian Athletics LLC, an independent software company. We're small, we train, and we build the tool we wanted to use ourselves.