Work
Designing HERCS: An AI-Powered, Sensor-Driven Fitness App
A Walkthrough of My Work
Project Overview
What is the project
The HERCS Mobile App and eBell transform weightlifting with smart, real-time tracking and optimization
Launched in 2021 by a passionate team of NYC fitness enthusiasts, HERCS™ introduces eBell—an innovative, auto-detecting fitness attachment designed for weightlifters. Coupled with a versatile mobile app, eBell adapts to various gym equipment, providing users with real-time tracking, personalized feedback, and AI-driven training insights.
Target Audience
We talked to 12 weightlighters across various fitness levels to explore their tracking experiences.
🤯 Too many options, hard to know what’s right.
📉 Plans didn’t adapt to their progress or needs.
🧩 Wanted personalized feedback, got vague advice.
Project Goal
How might we provide weightlifters with accurate, real-time tracking and personalized guidance to effectively optimize their workouts?
The Solution
With the challenges of target audience clearly identified, we’ve designed a user journey that improves their workout experience.
Timeline
I started the project in Feb 2023, and for about 7 months, I took ownership of the HERCS App design to the stage where we are preparing for the App to launch. On the side, I also designed HERCS’ website which was launched in July 2023.
Design Journey
What preparations did I make for the design phase? Let's explore my design journey!
Competitor Analysis
We found that individuals commonly enhance their fitness through personalized workout plans, strength-building exercises, and active participation in fitness communities
We selected a leading company from each category for our study.
Design Goals
The goal is to design an intuitive, motivating experience that supports weightlifters in the moment while building lasting engagement over time.
Initial Ideation
How can we integrate HERCS's experience into the current user journey to help resolving the pain points?
User insights shaped our initial wireframe, focusing on personalized plans, real-time tracking with eBell, and post-workout analytics.
Onboarding
Testing & Iterations
We defined four key questions to ask at the start:
Testing & Iterations
Users would go through a linear set of multiple-choice questions to quickly input their goals and preferences.
However, during user testing, we heard feedback: it lacked personality and flexibility.
The list felt tedious and limiting, and some users wished they could explain their needs in their own words.
How might we make onboarding more engaging and flexible-while still collecting structured data?
Design Solution
Instead of only offering predefined choices, we would also allow users to describe their goals in natural language.
The final onboarding design offers a dual experience:
1. A flexible input field where users can describe their needs directly to the AI.
2. A guided path with multiple-choice questions.
The AI coach processes user inputs to generate a personalized workout plan.
Users are welcomed with a tailored routine that reflects their goals, schedule, equipment, and focus areas.
Workout Session
Challenge
We were unsure whether users prioritized focus on the current exercise or access to their full workout plan.
User Testing
I conducted a focus group with early users and gave them both prototypes to try. Most users preferred the immersive view.
User Testing
To deepen our understanding, I also launched a short survey asking users to rank workout support features by importance.
“Exercise Demo” ranked highest, with real-time metrics and AI guidance tied closely behind.
The exercise list ranked lowest—reinforcing our decision to keep it as a secondary view.
-Jacqueline, fitness beginner, 29 yrs old
Design Solution
A Guided, Focused Exercise Experience
We focused the session view on the exercise demo and real-time metrics to keep users engaged.
A video demo shows proper form and tempo, paired with real-time metrics from the eBell sensor.
To further support users during their workout, we introduced two tiers of AI guidance:
The first tier of guidance offers light, encouraging prompts during the workout.
During workouts, the AI offers light voice and text prompts—like “Push harder”—to motivate without breaking focus.
The second tier of guidance delivers corrective feedback when form issues are detected.
When the eBell detects risky form, the AI steps in with a clear alert and offers a quick tutorial to help users correct it and avoid injury.
After each session, users receive a quick performance summary with key metrics.
The AI coach then provides personalized suggestions—adjusting weight, frequency, or intensity based on recent performance—to help users progress safely and consistently toward their goals.
Project Takeaways
