Luca Ferreira, Digital Product Design / UX Portfolio

Crusher Hand Trainer

The Crusher is a hand trainer with a built-in app that records your training and makes it motivating. While you train, you crack virtual nuts in the app and climb through different levels. That makes grip training playful and challenging, perfect for improving your own strength.

Note: role labels apply to all genders.

Role
Research
User Experience
Product Design

Timeframe
Apr 2023 - Jul 2023

Crusher hand trainer & app

Crusher app screens

Background: fitness with gamification

Recent studies show that grip strength is an important indicator of biological age and general health. Weak grip strength can point to many health problems. This insight inspired me to develop a hand trainer with an app that offers real-time feedback and history trends, so users can monitor their grip strength and notice changes over time.

But I did not just want to design another conventional fitness device. I wanted to create something people enjoy using. So I asked friends and acquaintances who do not do strength training about their reasons. The most common answer was that strength training is too monotonous: they find the exercises dull, and there is no playful or exciting component.

Inspired by this insight, I thought about how to build an interactive, motivating element into the design of a hand trainer. My goal was to create a device that is effective and fun at the same time. In my research I came across concepts that feel especially appealing, like playful elements and tangible moments of success. Many people are fascinated by destruction, as you see in games and trends. The visual and audible display of material being destroyed captivates a lot of viewers. That is how the idea came about to connect training with a virtual challenge. The resemblance of a hand trainer to a nutcracker inspired the concept that users crack virtual nuts through their training. This concept gives immediate, visual feedback of the strength you put in and creates a sense of achievement and power.

Problem: One challenge was to create a game experience that is accessible and motivating for every user, no matter their individual strength level. Rigid levels lead to either too little or too much challenge.
To solve this, the difficulty of the nuts was matched individually to the user's starting strength. That way everyone starts with a fair challenge and can keep improving while the game stays motivating.

To crack the walnut (level 1) you need 105 % of your initial maximum strength, which motivates you to improve right away.

105 % - Beginner: walnut
110 % - Pecans
114 % - Black walnut
126 % - Cashmere almonds
142 % - Brazil nuts
164 % - Macadamia nut

Background: fitness with gamification

Crusher level selection

Background: fitness with gamification

Crusher levels

To crack the walnut (level 1) you need 105 % of your initial maximum strength, which motivates you to improve right away.

105 % - Beginner: walnut
110 % - Pecans
114 % - Black walnut
126 % - Cashmere almonds
142 % - Brazil nuts
164 % - Macadamia nut

Crusher strength levels

UI design

The design of the Crusher hand trainer app stands out from cluttered fitness apps through simplicity and elegance. It uses the aesthetic-usability effect, which says that aesthetically pleasing designs are perceived as more user-friendly.

The clear interface focuses on the essential functions, reduces cognitive load and allows focused training. Warm tones and wood elements in the app pick up the nut theme and create a visual link to the physical hand trainer made of walnut wood. This supports a coherent experience and underlines the central idea of cracking nuts. The hand trainer and the app on their own act as a trigger to crack nuts.

Complex data is shown through intuitive graphics and illustrations, which makes the app accessible across ages. Overall, the UX/UI design of the app and the physical product brings together simplicity, elegance and function into a coherent, thematically consistent experience.

The grip

At the beginning I developed ergonomic grips that were meant to account for the shape of the hand and fingers. But there are too many different hand and finger sizes, so I decided to drop the idea and use a smooth surface instead. One element kept from these experiments is the taper of the wooden grip at the end, which also supports the little finger while gripping.

Crusher sketches (ergonomic grip)

Conclusion & learnings

Gamification and rewards are crucial for creating products that build new habits.

"Kill your darlings": no matter how much time went into an idea, if it does not work, you should let it go. The goal is to design the best possible product, not to keep everything just because a lot of time went into it.