Athlete-Led Fitness App Development with an AI Companion
A subscription-based fitness platform that combines training programs from professional athletes with personalized workout planning, an AI companion, and progress tracking.
The platform makes the training knowledge of professional athletes accessible through a mobile experience. Users discover athletes and sports, select structured training programs, follow video workouts, manage their training schedules, and track their progress.
Timspark joined the fitness app development project to audit the existing application, refactor its implementation, and deliver new features. The solution combines a React Native mobile application, a modular backend, and a Sanity content management system.
* The images are illustrative. Project details cannot be disclosed due to the terms of the NDA between the Development Team and the Customer.
industry
Sports & Fitness
services
Technical audit / mobile and backend development / AI integration / DevOps / release support
solution
Subscription-based mobile fitness platform
country:
United States
duration:
April 2026 – October 2026
Highlights
- Professional athlete content as the central product differentiator.
- AI assistance integrated into a structured fitness experience.
- Connected workout planning, scheduling, playback, and progress tracking.
- AI-first engineering using AI agents to automate routine tasks, improve code quality and accelerate delivery.
Challenge
The client needed to turn an athlete-led fitness concept into a coherent subscription product. The platform had to connect premium training content, personalized programs, AI assistance, and engagement features within a practical mobile experience.
A further challenge was reconciling the original product vision with an evolving implementation, including incomplete integrations and differences between planned functionality and delivered behavior.
The work required:
- Aligning the roadmap, designs, backend capabilities, and mobile implementation.
- Connecting athlete content, exercises, sessions, and programs into a consistent training journey.
- Keeping workout schedules and progress accurate across pauses, rescheduling, completion, and repeated sessions.
- Synchronizing subscription purchases with backend access permissions.
- Integrating conversational AI with training context and voice interaction.
- Delivering reliable video playback and responsive mobile screens.
- Completing challenge, badge, and leaderboard functionality.
- Resolving regressions across interconnected user flows.
Developing or improving a fitness app?
Connect training content, AI assistance, and subscriptions in one mobile experience. Connect training content, AI assistance, and subscriptions in one mobile experience.
Solution & functionality
The delivery approach combined mobile and backend development with systematic integration and validation of the core user journeys. An AI-first engineering approach helped the team automate routine tasks, improve code quality, and accelerate releases using AI agents.
The mobile application provides the training experience, while the backend manages accounts, workout plans, schedules, session activity, subscriptions, and engagement features. Sanity supplies structured training content and configurable AI settings.
Athlete-led training and personalized guidance
The content model connects athletes with sports, programs, sessions, and exercises. Training recommendations consider user preferences, while the AI companion explains and helps users navigate the content.
Users browse athletes and workout programs, select training based on preferences such as intensity, and follow guided video sessions with exercise information and playback controls.
Connected scheduling and progress tracking
Training calendars connect scheduled workouts with session activity and program progress. Users can adjust unfinished program sessions, provide pre-session input and post-session feedback, and review their workout history.
Challenges, badges, points, and individual or team leaderboards support motivation and continued participation. Training reminders and sharing of selected training moments extend the experience beyond individual sessions.
Content management and subscription access
The CMS allows the client to manage structured content and AI configuration. Subscription access and gamification support the commercial model and the goal of encouraging regular training.
Purchase integration connects subscriptions with entitlement-based access. Account functionality includes registration, authentication, profile management, and password recovery, while onboarding collects user information and training preferences.
Athlete-led programs
Users browse professional athletes, workout programs, sessions, and exercises.
Personalized recommendations
The app recommends programs based on training preferences, intensity, and the selected athlete.
Guided video workouts
Users follow video sessions with exercise information, playback controls, and session tracking.
Workout scheduling
Users manage their training calendars and reschedule unfinished program sessions.
AI fitness companion
Conversational AI helps users understand training content and navigate workout programs.
Progress and feedback
Users review workout history, track program progress and achievements, and provide session feedback.
Gamification
Challenges, badges, points, and individual or team leaderboards encourage regular participation.
Subscription access
Integrated purchases and entitlement management give subscribers access to premium training content.
Delivery model
Timspark Team
1 Full-stack React Native/Node.js engineer
1 Backend Node.js engineer
1 DevOps engineer
1 QA Engineer
Partner Team
1 Project Manager
1 UI designer (part-time)
1 ML/AI Engineer (part-time)
1 QA Engineer (part-time)
Timspark provided full-stack React Native/Node.js and backend engineers, supported by a part-time DevOps engineer. The partner handled project management and client communication, with part-time UI, ML/AI, and QA support.
Our scope covered mobile and backend development, third-party and CMS integrations, subscription access, configuration management, CI/CD, and development and production environments. Requirements, Figma designs, and a shared bug backlog guided delivery, with iterative builds, scenario-based testing, and defect verification.
Technologies used
React Native, Expo, TypeScript, Expo Router, Zustand, React Hook Form, Yup, Expo Video, React Native Reanimated, Skia, Three.js
Node.js, NestJS, TypeScript, REST APIs, PostgreSQL, TypeORM
OpenAI, Pinecone, Sanity CMS, React, AWS Cognito, RevenueCat, Stripe
Jest, Supertest, ESLint, TypeScript checks, Pino, OpenTelemetry, Expo Application Services
Results and business value
The delivered platform connects athlete-led content, training activity, and user engagement within one subscription product. It brings together accounts, training plans, scheduling, session tracking, subscriptions, AI conversations, challenges, and badges.
The client gained structured content management to maintain and expand the training library, personalized training journeys supported by recommendations and AI assistance, and a modular technical foundation for further product development.
AI-first engineering automated routine development tasks, improved code quality, and accelerated release delivery.
Unified training experience
Athlete content, workout planning, video sessions, and progress tracking in one product.
Subscription infrastructure
Integrated purchases and entitlement management for monetizing access.
Extensible content platform
CMS-managed training content and a modular backend for further development.
Maintenance handover
Release delivery and knowledge transfer to the client’s internal team.
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