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App & Features

Technology Improvements in the WHOOP Strap 3.0

May 30, 2019

Our entire team has been hard at work for over a year, learning from customer feedback and research and development to bring you a significantly more advanced product.

By John Capodilupo

Here at WHOOP, we’re very excited to have just released the WHOOP Strap 3.0 (“Gen 3”). Our entire team has been hard at work for over a year, learning from customer feedback and research and development to bring you a significantly more advanced product. I’d like to share a behind the scenes look at how we developed the technology, as well as give more details into some of the improvements we’ve made and what that means for your experience using WHOOP.

Gen 3’s electronics have been completely redesigned and upgraded from Gen 2. We learned a lot from the Gen 2’s out in the wild and from our members’ feedback about its performance. We discovered the biggest issues with the Gen 2 experience were the device’s battery life, and some band material not consistently holding the sensor securely in place.

WHOOP Strap 3.0 Hardware

To improve the battery life, we took a look at all of the ways the Gen 2 uses power. We decided the best course of action was to move the signal processing (which takes the sensor data and converts it into a heart rate) from the mobile applications to the Strap itself. By keeping the computations local to the Strap, we were able to gain several huge advantages.

First, we no longer needed to transfer tremendous amounts of raw data to another device over Bluetooth. This enabled us to use the much more power efficient and lower bandwidth Bluetooth Low Energy (BLE). Additionally, we didn’t have to worry about the occasional Bluetooth packet (bundles of information) loss that occurs when trying to transfer data from the Strap to the phone, which would cause retries in transmission or signal interruptions in our processing algorithms.

A hardware engineer making technological upgrades to the WHOOP Strap 3.0.

A WHOOP hardware engineer in action.

Porting the algorithm to the Strap was no easy feat–mobile devices have significantly more computational resources available to make it happen. But after months and months of effort we were able to get the algorithm to successfully run on the Strap itself, and in an acceptable time frame.

In addition to moving the algorithm, we undertook an extensive rebuild of the electronics as well. Gen 3 includes newer and more power-efficient components, like the microcontroller (similar in function to your computer’s processor) and accelerometer.

The combination of all of these things allowed us to increase the battery life from just under two days for Gen 2, to five days for Gen 3.

The mechanical structure of Gen 3 has also been upgraded. The casing and band attachment buckle have been strengthened, which will improve the physical durability of the Strap. Various other enhancements have also been made to enable a better manufacturing process for the Gen 3.

New Bands

To solve the issues some users had with band slippage (which in turn diminishes data accuracy), we sought to engineer a new type of band, custom made for WHOOP, that would fit our users comfortably and securely during all of their activities. The new ProKnit band features no-slip, quick-absorption and quick-dry properties. It’s also slightly stretchy, yet firm enough to hold the Strap securely in place. We’re very excited to have our users try the new ProKnit bands, they feel incredible on the wrist and function phenomenally!

Bluetooth Low Energy (BLE)

Beyond allowing us to significantly increase the battery life, BLE also gives us a more developer-friendly protocol with smartphones. The WHOOP App is now able to have much more control over the Strap and users will experience a more seamless pairing process.

BLE also enables several new app features, including the Strain Coach, WHOOP Live and Heart Rate Broadcast. For more on these features, check out our overview of the WHOOP Strap 3.0 and our recent podcast with CEO Will Ahmed.

Continuous Improvements

Just like our members, we are constantly hard at work using data to improve performance! This launch is just the start for Gen 3. We will continue to develop new features, data insights, and soft goods to enhance your WHOOP experience.

Stay tuned!

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John Capodilupo

John "Capo" Capodilupo is the Chief Technology Officer and Co-Founder of WHOOP. Capo leads technology strategy and development efforts across hardware, software, signal processing, and data science teams. Capo attended Harvard where he was studying astrophysics and computer science before dropping out to co-found WHOOP.