Jim Coach. Designing and building a mobile AI fitness app that earned 'App of the Day' on the App Store by solving the #1 gym problem: bad form leading to injuries.
01 — Market Research
Why existing fitness apps fail at the thing that matters most
I surveyed 100+ gym-goers and found that 73% had experienced an injury from poor form. Yet every major fitness app focused on rep counting and calorie tracking. The opportunity was clear: build the first app that actually watches and corrects your form.
02 — UI/UX & Brand
Designing for sweaty hands and quick glances
Mid-workout users can't read small text or tap tiny buttons. I designed a camera-first interface with oversized typography, haptic feedback for form corrections, and gesture-based controls. Every interaction was tested during actual workouts to ensure usability under physical stress.
03 — Development
Real-time pose estimation on mobile hardware
The biggest technical challenge was running TensorFlow Lite pose estimation at 30fps on mid-range phones without draining the battery. I optimized the model pipeline to use only 12 key skeletal points instead of the full 33, reducing inference time by 60% while maintaining form-correction accuracy.
04 — Go-to-Market
From launch to App of the Day
I executed a pre-launch strategy targeting fitness micro-influencers on Instagram and TikTok, generating 5K waitlist signups before launch. Post-launch, I optimized the App Store listing with A/B tested screenshots and keywords, leading to the 'App of the Day' feature within 6 weeks.
Project Outcome
“Featured as 'App of the Day' on the App Store.”
Jim Fitness