By Nicole Nguyen | Photographs by Jason Henry for WSJ
What's the best tracker? A fitness band? Smart ring? Smartwatch? Smart...shorts?
There was only one way to find out: I wore them all at the same time.
Trackers have really evolved, and beefed up on artificial intelligence. They can flag sleep apnea, predict illnesses -- even act as contraception. Studies show that tracking activity does spur people to move more. But the data influx can create excessive worry or an unhealthy obsession with achieving perfect scores.
I loaded up my limbs with a $399-and-up Oura Ring 5, a $100 Google Fitbit Air and a Whoop MG embedded in various clothing. (The Whoop tracker itself is included in the $199-and-up annual membership.) There are many benefits to going with one of these screenless options, namely better battery life and fewer distractions, though they lack the GPS tracking and access to emergency services available in smartwatches.
I did also wear an Apple Watch Series 11 ($399 and up). Fun fact: About 90% of smart-ring owners also own a smartwatch, according to research firm Circana.
During my three weeks covered in glowing sensors, I found myself toeing the line between mindful self-improvement and algorithmic overload.
Studying my sleep
Sleep is a core part of the wearables experience. The clinical standard for measuring slumber is an in-lab overnight study, or a polysomnogram. So off I went for a night at Stanford Health Care's Sleep Medicine Center.
The "lab" looked like a hotel room, though the ceiling-mounted camera and bedside monitoring equipment reminded me I wasn't on vacation.
The sleep technician glued electrodes to my head to measure brain waves. Next came leg-movement detectors, breathing bands, a microphone, a nasal airflow monitor and a finger pulse oximeter. The sensors transmitted my data wirelessly to overseers across the hall.
The next morning, I reviewed my results with Dr. Rafael Pelayo, a clinical professor of sleep medicine, who says a restorative night includes a mix of different stages: deep, REM (aka rapid eye movement) and lighter sleep, plus several micro-awakenings.
A sleep technician looked at my brain waves, muscle activity, eye movements and snoring audio to determine the stages. Even though the wearables can only infer the stages, using heart rate and movement data, they kept up pretty well.
The Apple Watch clocked the same sleep duration, down to the minute (six hours and 52 minutes) and its sleep staging aligned most with the lab results. The Fitbit Air was a close second, followed by Oura.
The Whoop tripped up early, mistaking my late-night reading for light sleep. Emily Capodilupo, senior vice president of research at Whoop, says its sleep algorithms have been validated against polysomnography, and peer-reviewed studies found its sleep detection reliable.
The wearables correctly identified REM cycles, but overestimated deep sleep -- the hardest stage to identify without brain-wave readings. While my polysomnogram showed just 28 minutes of deep sleep, each device said I got over an hour.
Average resting heart rate was better: All wearables were within one beat per minute of the sleep study. Oura got it exactly right, 59 bpm.
"A sleep tracker is equivalent to having a bathroom scale," says Pelayo. "It depends on how you use the tool." Since every scale is calibrated differently, what matters is whether the numbers trend up or down over time, he explained.
Reading my heart rate
I watch my pulse to gauge workout intensity. Some days require an all-out effort; others call for a lazy stroll. Plus, it's a measure of progress -- the fitter I get, the easier my heart works.
Wearables shine LEDs into your skin, monitoring blood pumping through your veins to infer heart rate. Thick hair, tattoos, darker pigmentation or aggressive movement can trip up sensors, says John Schuna, associate professor of kinesiology at Oregon State University.
During an indoor cycling workout, I tested the wearables against a chest strap that directly senses electrical heart signals. All of the trackers proved reliable.
There's a catch, says Schuna: The more active your hands are, the more faulty the sensor readings can be. During a bumpy outdoor bike ride and a chill walk with a stroller, only my Apple Watch remained relatively accurate.
The Apple Watch excelled across every activity. The Whoop could match it, provided I wore the sensor on my bicep. During periods of high activity, the Fitbit Air and Oura faltered.
Whoop's Capodilupo says the company is currently updating the heart-rate algorithm. A Google spokeswoman said the lightweight Fitbit Air is easier to move during more aggressive exercises, especially if the band isn't snug.
When I flagged the results to Oura, it noted that gripping a vibrating stroller presents a particular challenge for optical sensors. Also, there was a potential fit issue: The company sent a size 8 instead of my usual size 7. Unlike a band, you can't tighten a ring on the fly.
Dissecting my data
Each wearable's app has its own personality. The Apple Watch's Health app is the most basic, though it's end-to-end encrypted for privacy, even from Apple. Logged workouts are saved in Apple's Fitness app, which shows training load and other data.
The Fitbit Air's Google Health app is friendly. With a subscription, an AI-powered Health Coach generates easy-to-follow fitness plans. However, the AI tended to get carried away, for instance referencing my toddler in every insight. The Google spokeswoman said the company will address this "tunnel vision" in an update.
Whoop and Oura have polar-opposite personalities, but they tied for most useful.
Whoop is dark and data-dense. There's so much info, I found the pages hard to navigate at first. It's very fitness-oriented -- the AI-generated daily summary makes activity recommendations based on your metrics and offers a big workout "COMMIT" button as motivation.
Oura is calmer. Oura emphasizes recovery trends and makes fairly reliable predictions. On a day when other trackers said I was in "peak" shape or "primed" for training, it flagged "major signs" of strain.
Sure enough, I had a scratch in my throat and was more tired than usual. The next morning, I woke up feeling sick.
Unfortunately, Oura and Whoop achieve their higher quality through...higher costs.
Oura requires a $6-a-month subscription. Stop paying and it locks up your biometrics, leaving you with basic three-score feedback (sleep, readiness and activity). Whoop doesn't charge an upfront hardware cost but there's a mandatory membership starting at $199 a year. And the accessories -- bra, shorts, etc. -- aren't cheap.
That still isn't a lot to pay if you can get off the couch and build lasting change. But if you want data without a monthly fee, the pricier Apple Watch will provide it. And you can skip the Google Health $10-a-month premium plan and still use the Fitbit.
Living a healthy life is easy in theory but hard in practice. I welcome wearables steering me toward good choices, and decided the Oura Ring plus an Apple Watch is still the best combo for me. After a decade and a half of tracking my fitness, I've settled on using these devices to identify long-term trends and help me build better habits. Yet no matter how smart and capable they've become, they still can't replace my own body's intuition.
Write to Nicole Nguyen at nicole.nguyen@wsj.com
(END) Dow Jones Newswires
June 07, 2026 07:00 ET (11:00 GMT)
Copyright (c) 2026 Dow Jones & Company, Inc.
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