SB Fitness — React Native App

Overview

SB Fitness is a complete cross-platform fitness tracking application built from scratch with React Native and Expo. It covers the full workout lifecycle — planning programs, logging sessions, tracking personal records, and visualizing progress over time.

How It Works

Workout Tracking System

Real-time workout logging with weight, reps, and time tracking. Automatic 1RM (one-rep max) calculation using the Epley formula. Set completion tracking with visual feedback. Two modes: Free Workout (log anything) and Follow Program (guided session).

Program Builder

Multi-week workout program creator supporting 4–12 week programs. Day-by-day exercise scheduling across a 7-day cycle with configurable sets, reps, and rest periods per exercise. Full edit/delete with data persistence.

Exercise Database

100+ pre-loaded exercises across 11 muscle groups (Chest, Back, Legs, Shoulders, Arms, Core, etc.). Custom exercise creation with timed or reps options. Search and filter by muscle group.

Progress Tracking

• PR Tracker — automatic personal record detection with % improvement calculations
• Exercise History — last 5 performances with estimated 1RM progression charts
• Bar Chart Visualization — strength progression over time
• Calendar View — monthly workout overview with day-by-day completion
• Progress Photos — weekly uploads (front/side/back) with timeline view

Advanced Features

Superset Support with visual grouping (A1, A2, B1, B2). KG/LBS toggle with on-the-fly conversion. Workout state saved across sessions and resets daily. Rest day detection based on program schedule.

Data Architecture

Relational data modeling using JSON-based AsyncStorage with indexed key-value pairs. Efficient CRUD operations with async/await patterns, data integrity checks, and error handling throughout.

Technical Challenges

Managing complex relational state across React Native with AsyncStorage (no SQL available) required careful data architecture design. Workouts reference programs, programs reference exercises, and progress history references exercises — all of this had to be modeled in flat key-value storage with efficient lookup patterns.

Results / Status

A production-quality fitness app running on both iOS and Android with a full feature set comparable to commercial fitness apps. Built entirely solo as a personal project to learn React Native end-to-end.

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