Gymnasia

Mobile personal training app with AI assistant

Description

Gymnasia is a mobile application built with React Native and Expo that works as an intelligent personal trainer. The app allows you to create and manage workout routines, track your diet and body measurements, and features an AI chatbot that acts as a training assistant.

The project follows a local-first philosophy: all core functionality works offline, storing data locally on the user's device.

Key Features

Workout Routines

Create custom routines with exercises, sets, reps and weights. Each routine can be categorized (strength, cardio, flexibility, etc.) and customized with icons. During training, a rest timer with sound alert notifies you when to continue.
Exercise Library

Open-source exercise repository with AI-generated images showing correct execution, in both male and female versions. Exercises include muscle group, required equipment, difficulty level and detailed instructions. Users can also create custom exercises.
AI Assistant

Built-in chat with language models (compatible with OpenAI, Anthropic and other providers) that works as a virtual personal trainer. The chatbot has access to your routine context and can suggest exercises, answer technique questions or help you plan your training.
Diet Tracking

Daily meal logging with calorie and macronutrient calculation (protein, carbs and fats). Set personalized nutritional goals.
Body Measurements

Track weight and other body measurements with historical data to visualize your progress.

Architecture

The project is an npm workspace monorepo containing:

apps/mobile — Expo React Native app (primary surface)
apps/api — FastAPI Python backend
apps/web — Next.js frontend
packages/shared — Shared design tokens and TypeScript types
ejercicios/ — Open-source exercise repository (JSON + AI-generated images)

The mobile app uses AsyncStorage for local persistence and Expo SecureStore for API keys. Exercise images are served from the GitHub repository and cached on-device.

Technologies

Mobile: React Native, Expo SDK 54, TypeScript
Backend: FastAPI, Python, Alembic, Supabase
Web: Next.js, React, TypeScript
AI: OpenAI API, Anthropic API, language models as training assistant
Image Generation: Generative AI for exercise illustrations
Build: EAS Build for Android APK generation

Source Code

The project is open source and available on GitHub.

Support

If you like the project, consider giving it a star on GitHub.

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