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.”

Luke Michel has already lived through two technology overhauls in his career, first desktop publishing in the 1980s and online publishing later on. But AI? He’s had enough.

So when his employer, the Dana-Farber Cancer Institute, made an early-retirement offer to some staff last year, the 68-year-old content strategist decided to speed up his exit. Before, he had expected to work a couple more years.

“The time and energy you have to devote to learning a whole new vocabulary and a whole new skill set, it wasn’t worth it,” he said.

It isn’t that he’s shunning artificial intelligence—he is learning Spanish with the help of Anthropic’s Claude. But, at this point, he’s less than eager to endure all the ways the technology promises to upend work.

“I just want to use it for my own purposes and not someone else’s,” he said.

After rising for decades and then hovering around 40% in the 2010s, the share of Americans over 55 years old in the workforce has slipped to 37.2%, the lowest level in more than 20 years.

The financial cushion of rising home equity and stock-market returns is driving some of the decline, economists and retirement advisers say.

But for some older professionals, money is only part of the equation.

They say they don’t want to spend the last years of their career going through the tumult of AI adoption, which has brought new tools, new expectations and a lot of uncertainty.

Many people retire when key elements of their work lives are disrupted at once, said Robert Laura , co-founder of the Retirement Coaches Association and an expert on the psychology of retirement.

“Maybe their autonomy is being challenged or changed, their friends are leaving the workplace, or they disagree with the company’s direction,” he said.

“When two or three of these things show up, that’s when people start to opt out.”

“AI is a big one,” he adds. “It disrupts their autonomy, their professionalism.”

Michel, whose work required overseeing and strategizing on website content, has been here before.

When desktop publishing arrived in the 1980s, he was a graphic designer using triangles and rubber cement.

The internet’s arrival changed everything again. Both developments required new skills, and he was energized by the challenge of learning alongside colleagues and peers.

It felt different this time around. “Your battery doesn’t hold a charge as long as it used to,” he said.

He would rather spend his energy volunteering, making art, going to operas and chairing the Council on Aging in North Andover, Mass., where he lives.

In an AARP survey last summer of 5,000 people 50 and over, 25% of those who planned to retire sooner than expected counted work stress and burnout as factors.

About half of those retired said they had left work at least partly because they had the financial security to do so.

In general, older Americans are less likely than younger counterparts to use AI, research shows.

About 30% of people from ages 30 to 49 said they used ChatGPT on the job, nearly double the share of those 50 and older, according to a 2025 Pew Research Center survey of more than 5,000 adults.

Baby boomers and members of Generation X also experienced the sharpest declines in confidence using AI technology, according to a ManpowerGroup survey of more than 13,900 workers in 19 countries.

“We as employers aren’t doing a good enough job saying (to older workers), we value the skills that you already have, so much so that we want to invest in you to help you do your job better,” says Becky Frankiewicz , ManpowerGroup’s chief strategy officer.

Jennifer Kerns’s misgivings about AI contributed to her departure last month from GitHub, where the 60-year-old worked as a program manager.

Coming from a family of artists, she said, it offends her that AI models train on the creative work of people who aren’t compensated for their intellectual property. And she worries about AI’s effect on people’s critical-thinking skills.

So she was dismayed when GitHub, a Microsoft-owned hosting service for software projects, began investing heavily in AI products and expecting employees to incorporate AI into much of their work. In employee-engagement surveys, the company had begun asking them to rate their AI usage on a scale of 1 to 5.

When it came time to write reports and reviews, colleagues would suggest that she use ChatGPT.

“I’d be like, ‘I have no idea how to use that and I have no interest in using AI to write anything for me,’” she said.

It would have been more prudent to work until she was closer to Medicare eligibility, she said. But by waiting until her children were out of college and some of her stock grants had vested, the math worked.

Her first act as a nonworking person: a solo trip to Scotland, where she took a darning workshop and learned how to repair sweaters.

“The opposite of AI,” she said.

Employers already under pressure to cut workers—such as in the tech industry—may welcome some of these retirements, said Gad Levanon , chief economist at Burning Glass Institute, which studies labor-market data.

“The more people retire, the fewer they have to let go,” he said.

Some of the savviest tech users are also balking at sticking around for the AI upheaval. Terry Grimm, who worked in IT for 40 years, retired from his senior software consultant role at 65 last May.

His firm had just been acquired by a bigger firm, which meant learning and integrating the parent company’s AI and other tech tools into his work.

Until then, Grimm expected he might work a couple more years, though he felt that he probably had enough saved to retire.

“I just got to the point where I was spending 40 hours at work and then 20 hours training and studying,” said Grimm, who has since moved with his wife from the Dallas area to a housing development on a golf course in El Dorado, Ark.

“I’m like, ‘I’ll let the younger guys do this.’”

Health and Fitness Tracking Goes Mainstream

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

Their careers spanned the personal computing, internet and smartphone waves. But some older workers see AI’s arrival as the cue to exit.