Health and Fitness Tracking Goes Mainstream

Since September, Jeanette Cajide has armed herself with an Elite heart-rate variability monitor. And a temperature-controlled mattress pad. And a Levels continuous glucose monitor. And an Oura Ring that also measures heart-rate variability along with resting heart rate, respiratory rate and temperature. “Yeah, I’m a little crazy on the devices,” says Ms. Cajide, director of strategy and operations at consulting firm Clareo.

She’s got good reason. After returning to competitive figure skating four years ago, she won a national championship. Then last September, she broke her leg while landing an Axel jump. Ms. Cajide, who is 44 years old, competes again in eight weeks—against many skaters half her age.

She is trying to override nearly two decades as a “sedentary adult,” working in tech and investment banking. “I’m trying to make up for lost time. It’s me against time,” she says. “The sensors and data allow me to optimize for getting the most mileage out of my body.”

There is no escaping the Quantified Self movement. Measuring biomarkers used to be the preoccupation of extreme athletes and extreme geeks. No more.

“I think the attitude is shifting. The seriousness of the pandemic has made people realize that gosh, isn’t it a good idea to have a sensor,” says Michael Snyder, chairman of the department of genetics at Stanford University’s School of Medicine, whose research, among other studies, indicates data from smart watches—alterations in heart rate, steps and sleep—can be used to detect Covid-19 as early as nine days before symptoms.

Until relatively recently, health-minded people were excited to track their steps and heart rate. Now they can perform their own urine and blood tests, conduct body-fat scans and monitor their emotions. Soon they may be able to monitor their rate of aging to take steps to slow it down. Rings, watches, patches and apps that monitor biomarkers have taken off, buoyed by a pandemic that alerted everyone to “underlying conditions” they might not be aware of.

Fitness and tech companies, already adroit marketers, jumped on the opportunity, intriguing people like Ms. Cajide. They “have created this persona of somebody who’s striving and they’ve done a really good job of it,” says Joe Vennare, co-founder of Fitt Insider, which produces a newsletter and podcast and invests in health, wellness and fitness. Fitness-tech startups raised $2.3 billion in 2020, 30% more than the year before, according to market-intelligence firm CB Insights.

People who track their data are constantly sharing online. One recently tweeted a graph comparing her heart rate: “me walking alone, hauling it: 140 bpm vs. me walking normal with my friend: <110 bpm.” Another boasted that since he began wearing a sleep-tracking device, he has averaged 8.25 hours of uninterrupted sleep a night. Another tweeted eight separate graphs of jagged green and blue lines with an ominous question: “Anyone have heart rate or respiratory rate peaks in the night that is DOUBLE their normal value? I don’t know if this is a medical problem or just the measuring device.”

Self-trackers often fixate on factors that might influence their performance. “It’s interesting to look at these things and learn about yourself. They can help you understand things you couldn’t unearth on your own,” says Chris Bailey, co-founder and chief technology officer of startup NatureQuant and an endurance mountain biker. He’s currently testing the Apollo Neuro, which isn’t a tracker, but is considered another bio-hacking device designed to increase heart-rate variability and optimize performance. Worn on the wrist or ankle, it is designed to reduce stress and recalibrate the nervous system using varying-frequency vibrations that can be programmed to make you more alert in boring meetings, focus better during cognitive or athletic activities and recover more quickly after physical exertion. Mr. Bailey’s early verdict: “It’s a little hard to tell. It helps with focus a little bit, maybe, but it’s certainly not something that 2Xes your performance.”

Individuals react differently to caffeine, pasta, late nights—almost everything. Last year, Whoop added a journal to its sleep-tracking app. In the journal, users can log more than 70 behaviors to see how, over time, they might affect sleep and performance. Activities include taking medication like Advil, drinking wine, reading before bed and having sex. In a podcast introducing the change, Whoop executives said users had frequently requested the sex-tracking feature. For some, sex can raise core body temperature which is counterproductive to sleep, the company explained, so you might want to take that into account the night before a big event.

As for alcohol: Not a good idea, according to Whoop. While many people think alcohol helps them sleep better, it disrupts the repair and recovery that is supposed to happen during slumber. It interferes with physically restorative slow-wave sleep and it “crushes” your mentally restorative REM sleep, Emily Capodilupo, now Whoop’s vice president data science and research, explained in a company podcast. It messes with your heart rate, suppresses recovery and increases the chance of injury.

When Ms. Cajide, the figure skater, heard about sleep tracking, she thought it was silly. “I don’t care what happens at night,’” she recalls thinking. Then she learned the significance of heart-rate variability—not heart rate, which is beats per minute—but the variance in the length of time between heart beats. HRV is a key indicator of how fit, recovered and ready you are to perform, and can be greatly affected by the quality of your sleep. “I went down the rabbit hole,” she says.

Now she wears a continuous glucose monitor—a patch attached to the underside of her arm. Its data displays on her phone, telling her what foods are spiking her glucose and how efficiently she is managing her energy. She programs the temperature of her mattress pad to gradually fall to 62 degrees in the middle of the night, to bring down core body temperature and thus positively influence her heart rate and HRV. So far it has gotten those metrics to their “best points mid-sleep ever,” she says.

She uses her Fitbit as an alarm clock because its vibration doesn’t spike her heart rate and scramble her metrics. Then she checks the data from her Oura Ring and compares it to that of her Elite HRV, “to make sure they’re giving me the same information.”

The information tells her how hard to train—whether she will attempt an Axel, the jump that resulted in her broken leg last fall. Her current program includes two. “On a good recovery day, I’m more comfortable taking risks,” she says. That is crucial because she has only recently recovered but competes again in just eight weeks.

Dr. Snyder at Stanford understands the obsessiveness. He wears four smart watches, two on each wrist, to figure out what variables are the best to measure and “also sometimes one will run out of batteries.” He believes Ms. Cajide’s kind of self-tracking is critical to the future of healthcare, saying, “If people really care about their own health, they are going to have to take charge.”

AI agents like Muse can already find you the cheapest hotel room in Paris. But they can’t locate a cheaper version of that Catskills cabin you’ve been eyeing, because it might only be available on Airbnb ABNB -1.43%decrease.

Investors should pay attention to that distinction. When Meta Platforms META 3.38%increase launched its Muse agent last month, travel stocks including Booking Holdings BKNG -1.19%decrease, Expedia and Airbnb all fell sharply.

Airbnb, though, has a real chance to emerge as a winner from the upheaval. The catch: Its stock already reflects above-industry growth. To justify its valuation, Airbnb will need to turn repeat customers into loyal ones.

Online travel companies make much of their money by simplifying search and collecting fees on bookings. AI agents threaten that model.

But not all travel marketplaces are equally exposed. Booking and Expedia largely sell hotel rooms that travelers can also book directly or through competing sites. If an agent can find the same room elsewhere, it has little reason to favor either Booking or Expedia.

Booking and Expedia also sell sponsored listings that steer travelers toward particular properties. Wells Fargo estimates those will account for about 8% of Expedia’s revenue and a much higher percentage of profit next year.

Airbnb has more ways to adapt. More than half its listings are available only on its platform, and more than 90% of its traffic comes directly to its app or website.

The customer relationship doesn’t end after booking, either. Bernstein analyst Richard Clarke notes that 90% of Airbnb guests go on to message their hosts about arrival times, keys or local taxes, giving Airbnb a connection to both sides of the transaction.

How the companies have responded to the possible agentic future is telling.

Expedia quickly signed on as a Muse partner. Airbnb hasn’t, and Chief Executive Brian Chesky says AI chatbots have so far been a boon, sending customers to Airbnb’s website.

Chatbots might work for buying paper towels, he quipped at a Skift conference last month, but people enjoy planning trips. He argued that browsing dozens of homes isn’t something a text-based chatbot is well suited for.

Still, the AI jitters arrived just as Airbnb was persuading investors it deserved its pricey multiple. For years after its 2020 initial public offering, the stock—which trades around 25 to 30 times forward earnings—went nowhere. Investors saw a mature operator trading at a growth premium.

This year, Airbnb growth seems to be accelerating. The stock jumped in August after the company raised its full-year revenue-growth guidance with its second-quarter results. Wells Fargo analyst Ken Gawrelski credits a run of product improvements under a revamped leadership team.

Among the changes: letting guests reserve now and pay later, adding hotels, and a redesigned home page and app. Investors were also betting on what comes next, including thousands more hotels, car rentals and, eventually, advertising.

The irony is that some of those growth drivers push Airbnb closer to the kind of business Booking and Expedia run—the kind of business AI agents could threaten. Even if AI agents capture a large share of travel planning and booking, Airbnb would capture the demand. But it and others would slowly lose control over how customers find and choose properties.

That would undermine the advertising opportunity investors are counting on. The bigger point for Airbnb and other marketplaces is that losing control of customer acquisition could mean surrendering some of their pricing power and margins.

To bulletproof itself, Airbnb might look to another e-commerce giant that has so far kept AI agents at arm’s length: Amazon.

Like Amazon, Airbnb has a loyal customer base and hard-to-match supply. But it has nothing like Prime membership to make customers think twice before taking their business elsewhere.

That is where loyalty comes in. Business travelers stick with Hilton or Marriott because enough nights earn them perks. Leisure travelers rarely accumulate stays with one chain. Airbnb has millions of listings and plenty of repeat customers, but no broad rewards program. It has begun experimenting with credits on hotel stays, but it should make loyalty a priority, not just a promotion.

Airbnb also plans to launch its own AI agent next year. But travelers using an agent might still want it to search Airbnb, Vrbo, Booking and hotel websites alike, rather than limit itself to one company’s inventory.

Eventually, Airbnb might have to strike deals with agent makers, using its unique homes as leverage to negotiate favorable terms, says Gawrelski. Such deals, along with rewards for loyal guests, could over the long term eat into the company’s roughly 13% take rate, he adds. But if they bring in enough additional bookings, the trade-off could be worthwhile.

History offers a reason not to panic. The shift from desktop to mobile unsettled investors in Alphabet and Amazon, but both emerged as major beneficiaries. Companies with valuable assets can come out of a platform shift stronger, if they adapt quickly enough.

Airbnb has homes the bots can’t easily replace. Now it needs to give guests a reason to insist on booking them there.

Health and Fitness Tracking Goes Mainstream

Self-tracking has moved beyond professional athletes and data geeks.

AI-powered travel agents are challenging online booking platforms, but Airbnb’s exclusive listings and direct customer relationships could give it an edge. Its next challenge: turning repeat guests into loyal customers through stronger rewards and innovation.