Inside the rise of Whoop, Boston’s fitness-wearable tech giant

Will Ahmed, the Harvard squash captain-turned-entrepreneur, was at his parents’ house on Long Island six years ago, watching a basketball game. During the break, a Kia commercial featuring LeBron James came on, and Ahmed noticed something on the NBA star’s wrist.

It was a Whoop, a fitness wrist strap created by Ahmed’s company, which tracks heart rate and sleep data, and streams it to a customer’s mobile phone app.

Ahmed would never forget that moment. Still early in Whoop’s history, he was smarting from hundreds of investor rejections. His company wasn’t showing meaningful revenue. The market for fitness straps was flooded, and sports giants like Nike, Under Armour, and Adidas were the competition. But the commercial showed Ahmed something important, he said.

“It’s like, wow, one of the world’s best athletes is getting so much value out of this technology that he literally won’t take it off,” Ahmed said in an interview. “It’s like, ‘we’re on to something.’”

The SuperKnit Band is part of the new Whoop 4.0.Pat Greenhouse/Globe Staff

Fast forward to the present day, and Whoop is one of the most valuable fitness-wearable startups in the world, topping $3.6 billion in value with its latest investment round last week. Elite athletes like Michael Phelps, Patrick Mahomes, and Justin Thomas flash the devices on their wrists. The COVID-19 pandemic has unlocked some clinical applications for the product. And on Wednesday, the company released its most advanced products yet, with new tracking features in its wrist band and an apparel line that lets users embed sensors in workout garments.

Whoop was founded back in 2012. It was Ahmed’s brainchild, born out of his desire to track how efficiently he was working out. A college athlete and government major with little science background, Ahmed said he read hundreds of medical papers. In study after study, he found that if athletes rigorously tracked certain metrics, like the variability in their heart rate, they could learn if their body was ready to work out or needed rest.

But how do you build something small enough to track this data, make it comfortable enough to wear continuously, and build a brand around it? he asked. “I put on a pair of Air Jordans, I feel like I should go work out,” he said. “How powerful would it be if you could have the same coolness factor that you associate with Air Jordans, but in a wearable tech?”

Will Ahmed is founder and CEO of WHOOP, a fitness wearable company. He holds the new WHOOP 4.0 sensor.Pat Greenhouse/Globe Staff

Ahmed scoured Harvard’s student body for potential cofounders, looking for people with technological acumen. Through friends, he met John Capodilupo, a fellow Harvard student. Impressed that Capodilupo was taking Harvard’s “Math 55,” which Ahmed said was one of the hardest math classes in the country, he asked him to join.

Capodilupo told Ahmed that Aurelian Nicolae, a Romanian student living on a couch in his house, excelled in mechanical engineering at Harvard and could be a good fit for the company. The trio got to work on the Whoop prototype out of the Harvard Innovation Lab.

Ahmed, an only child with an Egyptian immigrant father and American mother, raised about $300,000 from family and friends to start the company. Roughly $700,000 more came from angel investors interested in early-stage technology. (Now, its lead investors include Japan’s SoftBank Vision Fund 2.)

Whoop launched its first product around 2016, focusing on professional athletes. Shortly after, it released a version of its wrist strap for consumers, costing $500, with the proposition that normal people could “get all the same analytics as the best athletes in the world,” Ahmed said.

Over the next 18 months, the startup didn’t sell many straps, he said, but those who were buying it continued to wear it. At the same time, Peloton, the at-home fitness bike company, was pioneering a subscription-based business model, which Ahmed was inspired by.

That gave birth to Whoop’s current business, where the fitness strap is free, and users pay around $30 per month to access the health metrics it tracks.

On the company’s app, customers can see their “recovery score,” which combines heart, sleep, and body stress data into a number that puts users in a “Green,” “Yellow,” or “Red” workout range. In its newest model — the Whoop 4.0 — blood oxygen and skin temperature levels can also be tracked. Whoop Body, another new product, will let members put the company’s LED sensors into garments the company now makes, effectively making the device invisible.

The WHOOP 4.0 (not shown) and WHOOP Body (two on left for women; two on right for men) are being announced Wednesday, September 8, 2021.Pat Greenhouse/Globe Staff

Since the company’s early days, professional athletes have been a crucial marketing tool. Colleen Quigley, a 2016 member of the US Olympic team for steeplechase, is an ambassador for the product. She said it is not uncommon for the athletes she coaches at Portland State University to ask if the product is really worth it.

Quigley tells them how Whoop has helped her rigorously track the quality of her workouts and, most importantly, suggested when she should rest. It’s perfect for elite athletes, she said. “We love numbers, we love data, we love learning about ourselves, and we’re always getting injured.”

Meanwhile, the pandemic has encouraged the company to work on clinical applications as well. In March of 2020, Whoop released an application update where Whoop users could track their COVID-19 status.

Whoop officials noted that many of their users who contracted COVID-19, including the professional golfer Nick Watney, saw their respiratory rate spike days before receiving a positive diagnosis. Ultimately, the startup partnered with Central Queensland University in Australia and published a medical paper examining the utility of wearable health technology in predicting COVID-19 infections.

“It really made us realize the power that we have with this data,” Capodilupo, the company’s chief technology officer, said. “It really got us interested in contributing and developing features more for the health space.” (When asked, Ahmed would not confirm if Whoop has applied for approval as a medical device from the Food and Drug Administration.)

Despite the testimonials, multi-billion-dollar valuation, and roughly $400 million in capital raised to date, the company still has a long way to go in the fitness world. Tech titans like Apple and Google — through its purchase of Fitbit — are looking to own the sector. Perhaps for competitive reasons, Whoop remains quiet about its revenue, membership base, and how popular the product actually is.

Michael Greeley, cofounder of the Boston-based venture capital firm Flare Capital Partners, said Whoop’s $3.6 billion valuation might not be reflective of its current financial performance, but its future. (Greeley is not involved with the company.)

“If you’re just following the product sales ... you wouldn’t get that price,” he said. “It’s the data component, I think, where investors are saying, ‘Wow, that’s very valuable.’”