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The Scientist's Notebook for Endurance Athletes.

Real physiological models on your phone. Gradescale runs the same analytics used by professional coaching staff — directly from your Strava data, on-device, with no black-box score names.

About Gradescale

Gradescale is a training analytics app for endurance athletes who want to understand what their data actually means. It fits a power-duration model to your activity history, tracks load balance using exponential moving averages, and surfaces aerobic decoupling metrics derived from heart rate vs. pace or power over time. The models run on-device after a one-time Strava sync — no cloud processing, no proprietary score names, no vendor lock-in.

The design principle is insight delivery over chart building. Most training apps show you the numbers; Gradescale tells you what they mean relative to your own baseline. Readiness scores, load balance trends, and power-duration curve shifts are all framed in plain language with the underlying math visible for athletes who want to dig in. Available on iOS, Android, and web.

Founder

Thomas Mortelmans

Thomas Mortelmans is a Belgian endurance athlete and software developer who built Gradescale to solve a problem he kept running into: the analytics tools worth using were either desktop-only or locked behind proprietary metrics that obscured more than they revealed. He trained and raced while building the app, running the models on his own data first. He also runs ESQ Coaching, an endurance coaching practice where the same physiological frameworks power athlete programming.

Product Screenshots

High-resolution screenshots available on request at press@gradescale.fit.

[SCREENSHOT: Dashboard — chronic/acute load chart + readiness score card]

Training Load dashboard showing load balance trends and daily readiness

[SCREENSHOT: Power-Duration Curve — fitted model overlay on raw data points]

Power-duration model with estimated functional threshold and anaerobic capacity

[SCREENSHOT: Analytics — aerobic decoupling breakdown for a recent long ride]

Aerobic decoupling analysis highlighting cardiac drift across effort zones

Brand Assets

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FileSizeUse case
icon-180.png180×180 pxiOS home screen icon, Apple TouchDownload
icon-512.png512×512 pxAndroid icon, web app manifestDownload
app-icon-1024.png1024×1024 pxApp Store / Play Store submission, high-res printDownload
instagram-profile.png320×320 pxInstagram profile picture, social avatarsDownload

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Quote-Ready Blurbs

These are cleared for direct use in editorial copy without further approval.

1-sentence

Gradescale is a mobile training analytics app that applies the same physiological models used by professional coaching staff — power-duration curves, aerobic decoupling, load balance tracking — directly on your phone.

1-paragraph

Gradescale is a mobile-first training analytics platform for endurance athletes. It models power-duration relationships, tracks chronic and acute load balance, and surfaces readiness scores derived from heart rate decoupling and recovery markers — all running on-device from your Strava data. The goal is insight delivery, not chart building: the app tells you what the numbers mean, not just what they are.

1-paragraph with data

Gradescale is a training analytics app that brings evidence-based physiological modeling to everyday athletes. Using a 3-parameter power-duration model fitted to your activity history, it estimates functional threshold power, anaerobic work capacity, and aerobic decay over any duration. Load balance tracking uses exponential moving averages over 42-day and 7-day windows to quantify training stress without proprietary score names. Built for iOS and Android, the app processes data locally from Strava — no subscription required to access core analytics. Gradescale launched into waitlist beta in 2026.

Quick Facts

Founded
2026
Team size
1 (solo founder)
Platforms
iOS + Android + Web
Data source
Strava API
Waitlist members
[PLACEHOLDER]
Core algorithms
20+ modules