Developing WHOOP 4.0: Product Validation in the WHOOP Labs

A look behind the scenes at how we built the 4.0, and the research and product validation we do at WHOOP Labs.

Our goal for WHOOP 4.0 was to make a product that was smaller, more accurate and customizable, and with a sleeker charging experience. Pulling this off was no easy feat. In fact, we actually began working on WHOOP 4.0 back in 2018 and tested prototypes for 21 months in our Boston-based WHOOP Labs. When it was all said and done, we successfully decreased the volume of WHOOP 4.0 by 33% while maintaining 5-day battery life, introduced wireless charging and a waterproof battery pack, increased modularity to allow wearability throughout the body as well as seamless swapping of bands, and also added SpO2 monitoring, skin temperature detection and a haptic alarm feature.  

Designing WHOOP 4.0

Using our previous datasets and benchtop analyses, we worked to align on configurations for the WHOOP 4.0 that had the most potential for improving accuracy in a smaller form factor. While doing this, we separated our production into two streams--sensor design and industrial design. For our sensor design project, we began with the existing WHOOP 3.0 form factor and tested over two-dozen different sensor configurations. These prototypes were all handbuilt in house with the aim of identifying a configuration that allowed for increased accuracy across a wide range of conditions. Our team also tried hundreds of different strap configurations, toying around with layout, size, lens height, slider style, and topography of the sensor as we worked to finalize our industrial design.  

WHOOP Labs: Real-World Research and Product Validation

Throughout these processes our design teams partnered closely with the team at WHOOP Labs, collecting data using next-generation prototypes in real-world environments to continually refine, iterate, and produce the best possible end product. Located in Boston, WHOOP Labs is the research and product validation branch of the company. WHOOP Labs executes studies on participants of varying ages, fitness levels, skin tones, genders, and handedness. Whether you are a WHOOP member or not, you are welcome to take part in a WHOOP Labs study. Testing our straps on a wide range of participants to constantly improve our product is a critical part of our work here at WHOOP, and we are so grateful for the enthusiasm shown by everyone who walks through the doors of WHOOP Labs.

A sample of WHOOP Labs study participants.  

Testing WHOOP 4.0

The WHOOP 4.0 development campaign included over 4,000 participants and 20,000 data sets. This enabled our signal processing team to refine and train our algorithms for our members by analyzing thousands of data sets from a range of participants engaging in various activities. Early in 2020, we began testing unique configurations of our sensors using our 3.0 form factor. We were working out of WHOOP HQ as we aimed to narrow down our handmade prototypes with the strongest potential to be our WHOOP 4.0. As COVID-19 became a prominent concern, WHOOP Labs adopted additional hygiene policies, started wearing masks and gloves, and socially distanced participants. Shortly after instating COVID-19 safety protocols, WHOOP Labs had to halt operations due to the COVID-19 pandemic on March 15, 2020. Validation on participants is key to moving forward and refining our products, so as soon as we were safely able to get back to the lab, it was critical to get our in-person testing back in action.  

Adjusting on the Fly

WHOOP Labs was able to resume operations and welcome participants back into the Lab in July of 2020. At that time we opened our first WHOOP Labs location outside of the office, allowing us to safely conduct studies while socially distanced, masked, and following a strict sanitation and hygiene protocol. We started to branch away from our general fitness studies and incorporate studies such as indoor spinning, yoga, indoor running, weightlifting, and functional fitness. The goal was to mimic activities that our members engage in to ensure that WHOOP 4.0 collects data accurately during various activities. Through this process, our team worked to narrow down which of the in-house, handmade prototype straps had the most potential.

"Study Pods" in the WHOOP Labs.

The Boston WHOOP Labs moved to its current location in January of 2021, which has the capacity to run four studies simultaneously, each in a private and dedicated “study pod.” At this point, we also sent a team to Austin, Texas to conduct our outdoor field research, taking advantage of the sunny, warm weather conditions that Austin has to offer.

WHOOP Labs went on the road to Austin, TX For outdoor field research.

Through the winter and spring of 2021, WHOOP Labs accelerated testing and aligned on the final design for WHOOP 4.0. Boston and Austin each saw 20-30 participants per day from 8:00 am until 8:30 pm, effectively pressure testing the prototypes in all conditions the straps might encounter in the wild.  

A Variety of Studies

The WHOOP Labs team utilizes local golf courses, the open water at Walden Pond in Concord, MA, outdoor cycling routes, tracks, basketball courts, and turf fields among our many testing grounds. We also regularly bring in Boston-based fitness instructors to lead classes in our Lab so we can better study various activities.

A fitness class at WHOOP Labs collecting data from specific activities.

WHOOP Labs began sending 4.0s to Australia for use in a sleep lab monitoring and testing its sleep metrics, including the new pulse oximeter. The team also started conducting studies in an altitude tent where participants were taken up to an elevation of 22,000 feet, effectively creating scenarios where we would see low oximeter levels, and stress testing the 4.0.  

Creating WHOOP Body

Alongside the development and validation of WHOOP 4.0, our apparel team also began creating WHOOP Body featuring Any-Wear Technology. In tandem with the 4.0, we are proud to release a sports bra, legging, two styles of bralettes, a compression top, a performance boxer, and a cotton boxer, all of which enable you to wear WHOOP away from your wrist. At the forefront of our minds throughout this process was the intent to make wearable technology truly wearable. The result was a technical line of apparel that suits our members’ lifestyles through intimates they can wear all day, and a training range that offers high-performance fabrications as well--all while creating an innovative product that allows the 4.0 to accurately pull raw data from a variety of places on the body. By decreasing the volume and increasing the modularity of WHOOP 4.0, it is easily detachable from the band to seamlessly slide into pods (small pockets that hold the sensor against your skin) in WHOOP Body garments. Choosing which places on the body to insert the pods in our WHOOP Body garments was a creative process. We first used a thermal gun to see which areas on a person’s body had the most blood flow and would give the most accurate data readings for our members. From there, we decided to look at 20 different locations by sticking WHOOP 3.0s on test subjects and putting athletic tape over the straps to assess which ones worked best. The WHOOP Labs team executed hundreds of studies and worked closely with our signal processing team to deduce which locations accurately collected data.

Early testing for potential WHOOP Body pod locations.

Once we had a grasp on the best places to collect data, the next step was to safety pin WHOOP 3.0s in our activewear and put them on participants. WHOOP Body went through several full garment revisions, with many versions of the pod we use to hold 4.0 securely in place, and also testing the pods in various spots within each piece of clothing. In the end we settled on bicep, side torso, glute, and calf as the ideal places to wear WHOOP off your wrist.  

Fit and Accuracy

After determining the locations and garments that deliver the highest quality data for our members, we went to work on confirming how those garments would fit our diverse membership base. As with the 3.0, the WHOOP 4.0 requires constant skin contact in order to produce the most accurate and reliable data. To do this with our WHOOP Body apparel requires all the garments to fit snugly--and because our members come in all shapes and sizes, the sizing and grading of our pieces needs to be dialed-in. Over the course of thousands of wear tests and fittings, we optimized the sizing and grading rules of our garments to ensure that we were maximizing data collection. Having the right size garment is critical to data integrity, so it’s extremely important that when selecting WHOOP Body pieces our members utilize the size guide to choose what is right for them. Launching WHOOP Body is a great way to give our members a choice in how they want to wear their 4.0. For those who would prefer not to have a wearable on their wrist, feel restricted in their activities, or are prohibited from wearing a device there during work or athletic competition, the ability to slip WHOOP 4.0 off of your wrist and easily slide it into one of our garments is a game changer.  

Join the WHOOP Labs Experience

WHOOP Labs is an integral part of the validation of our product. Better yet, it is also a place that we see our members coming back to, finding value and excitement in being part of the development process of our product. Some first-time participants are WHOOP members and some are not, and many become members after experiencing and learning about the product in our lab. WHOOP Labs have come a long way in the last few years. We started inside the WHOOP office, moved to our first dedicated lab space, and are now in our second lab space, on top of a three-month period of field operations in Austin, Texas. If you have not stopped by WHOOP Labs yet, it is an amazing way to be at the forefront of the company’s research and feel connected to the product. Without our extraordinary participants the development and validation of WHOOP 4.0 would not have been possible, and we will continue to rely on them to help us create an innovative product that keeps up with the changing world. We are grateful for all of our participants - members and non-members - and look forward to meeting new ones every day.   Sign up to be notified of WHOOP Labs studies near you!