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.”

David Beckham was at the World Economic Forum in Davos, Switzerland, on Tuesday with Bank of America chief executive Brian Moynihan to promote their new partnership. But all anyone wanted to talk about was his son.

After the obligatory questions about business and the World Cup, a host on CNBC’s “Squawk Box” lobbed Beckham an out-of-left-field query about how young people can preserve their mental health in the age of social media.

“Children are allowed to make mistakes,” Beckham, 50, said. “That’s how they learn. So, that’s what I try to teach my kids, but you have to sometimes let them make those mistakes as well.”

Just a day earlier, his 26-year-old son Brooklyn Beckham had posted a series of accusations about his soccer-famous father and pop-star-turned-fashion-designer mother, Victoria Beckham.

He said that his parents had controlled him for years, lied about him to the press and sought to damage his relationship with his wife, Nicola Peltz Beckham. Their goal, he said, was to affect the image of a “perfect family.”

“My family values public promotion and endorsements above all else,” he wrote on Instagram. “Brand Beckham comes first.”

That brand has been burnished over decades of professional triumphs, tabloid scandals and slick dealmaking.

Recently, both David and Victoria Beckham put their legacies on-screen in docuseries that cast them as hardworking entrepreneurs and devoted parents. Their image appeared stronger than ever. Now their firstborn child is throwing stones.

Representatives for David Beckham, Victoria Beckham and Brooklyn Beckham did not respond to requests for comment. A representative for Nicola Peltz Beckham declined to comment.

In the U.K., the Beckhams are as close as you can get to royalty without sharing Windsor DNA. David is perhaps the most famous English player in soccer history, while Victoria parlayed her Spice Girls fame into a career as a respected fashion designer.

Their partnership was forged in the cauldron of 1990s celebrity gossip, with their every move—in their careers, their bumpy personal lives and their adventurous senses of personal style—subject to tabloid scrutiny.

“They were Taylor Swift and Travis Kelce before Taylor Swift and Travis Kelce,” said Elaine Lui, founder of the website Lainey Gossip.

Over time, the couple became savvy managers of their own brand, a sprawling modern empire including a professional soccer team, fashion and beauty lines, investment deals and commercial partnerships.

In recent years they each released a Netflix docuseries—“Beckham” in 2023, “Victoria Beckham” in 2025—featuring scenes from their private family life. (Brooklyn and Nicola appeared in David’s series, but not Victoria’s.)

“The way they’ve performed their celebrity has been togetherness,” Lui said: Appearing and engaging with the world as a happily married couple, in both relative calm and amid scandal. And as their family grew, their four children became smiling ambassadors for Brand Beckham, too.

Until Monday night. In a series of Instagram Story posts, Brooklyn accused his parents of “trying endlessly to ruin” his marriage to Nicola, an actress and model, and the daughter of billionaire investor Nelson Peltz . Brooklyn declared, “I do not want to reconcile with my family.”

Where Victoria and David seemed to see press scrutiny as part of the job, Brooklyn and Nicola are operating in a manner more typical of their own generation. Brooklyn’s posts call to mind the “no contact” boundaries some children have enforced with their parents in recent years to much pop-psych chatter.

Andrew Friedman, managing director of crisis communications at Orchestra, said he’d advised many clients through family drama. “Going public,” he said, should be a “last resort.”

He’s also warned clients that using social media to air grievances opens a can of worms. “Nuance is not welcome in social-media feeding frenzies,” Friedman said. “Sensational and unusual details will overshadow the central issue.”

Brooklyn, the eldest of the Beckhams’ four children, has built a following in his parents’ image, though without the benefit (or burden) of a steady career.

He’s worked as a model, photographer, cooking-show host and most recently founded a hot-sauce brand. Brooklyn and Nicola went public with their relationship in 2020 and married in a lavish 2022 ceremony at her family estate in Palm Beach, Fla.

Rumors of a family feud flared almost immediately after the wedding, including whispers about the fact that Nicola didn’t wear a dress made by her fashion-designer mother-in-law.

Brooklyn on Monday recounted further grievances related to a mother-son dance and the seating chart. In the months and years that followed, celebrity journalists and fans closely tracked both generations of the family, looking for cracks in the relationship.

But official dispatches from Beckham World suggested that things were just fine. In a scene from the final episode of David’s Netflix series, the Beckham family, including Brooklyn and Nicola, joke around on a visit to their country home. It’s a picture of familial bliss.

“We’ve tried to give our children the most normal upbringing as possible. But you’ve got a dad that was England captain and a mom that was Posh Spice,” David says in voice-over.

“And they could be little s—s. And they’re not. And that’s why I say I’m so proud of my children, and I’m so in awe of my children, the way they’ve turned out.”

Health and Fitness Tracking Goes Mainstream

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

In a series of social-media posts, the eldest child of David and Victoria Beckham threw stones at the image of a ‘perfect family’.