Mobile Fitness App

# Requirements Specification: Mobile Fitness App

## Overview
A mobile app for tracking workouts, following exercise programs, and monitoring fitness progress over time.

## User Personas

### Fitness Beginner
- Needs guided workout programs
- Wants simple exercise instructions with videos
- Tracks basic metrics (workouts/week, calories)

### Gym Regular
- Creates custom workout routines
- Tracks weights, sets, reps over time
- Wants progress charts and PRs

### Social Fitness Enthusiast
- Shares workouts with friends
- Participates in challenges
- Motivated by streaks and achievements

## Features

### F1: Workout Tracking
**Priority:** P0 - Critical

#### User Stories
- As a user, I want to start a workout and log exercises
- As a user, I want to track sets, reps, and weight
- As a user, I want rest timers between sets
- As a user, I want to see workout history

#### Acceptance Criteria
- [ ] Workout session with exercise list
- [ ] Log sets: weight (lbs/kg), reps, RPE (optional)
- [ ] Rest timer with configurable duration
- [ ] Workout saved with duration and volume
- [ ] Offline support - sync when online

### F2: Exercise Library
**Priority:** P0 - Critical

#### Acceptance Criteria
- [ ] 200+ exercises with muscle groups
- [ ] Video demonstrations
- [ ] Text instructions and tips
- [ ] Search by name or muscle group
- [ ] Filter by equipment (barbell, dumbbell, bodyweight)

### F3: Programs & Routines
**Priority:** P1 - High

#### User Stories
- As a beginner, I want pre-made programs to follow
- As a gym regular, I want to create custom routines
- As a user, I want program schedule with rest days

#### Acceptance Criteria
- [ ] 5 built-in programs (PPL, Starting Strength, etc.)
- [ ] Custom routine builder
- [ ] Weekly schedule view
- [ ] Program progress tracking

### F4: Progress & Analytics
**Priority:** P1 - High

#### Acceptance Criteria
- [ ] Charts: volume over time, estimated 1RM
- [ ] Personal records per exercise
- [ ] Body measurements log
- [ ] HealthKit/Google Fit sync (steps, calories)

### F5: Social Features
**Priority:** P2 - Medium

#### Acceptance Criteria
- [ ] Follow friends
- [ ] Activity feed (workouts completed)
- [ ] Monthly challenges
- [ ] Achievements and badges
- [ ] Workout sharing (optional)

### F6: Subscription (Premium)
**Priority:** P1 - High

#### Free Tier
- Basic workout logging
- 5 exercises tracked
- 1 week history

#### Premium ($9.99/month)
- Unlimited exercises
- Full history
- Programs
- Analytics
- No ads