“I just hit 20,000 steps!” my husband exclaims as he brags when his fitness tracker exceeds the oft-heard benchmark of 10,000 steps per day.
Although I rarely get that many steps, I use my wearable health tracker to monitor my fast heart rate in order to give my cardiologist concrete numbers.
Today’s health wearables have evolved from simple step counters to “mini-clinics” on our wrists that can be used for many different purposes and provide us with a wealth of information as a first step in monitoring our overall health. However, while these trending devices are powerful, they aren’t diagnostic medical tools.
“As with any innovation, these tools bring both promise and perils. They are a source of more data; the devil lies in how we use the data, and the context in which we interpret them,” says Dr. Matthew Tomey, a cardiologist at Mount Sinai Fuster Heart Hospital in New York City.
Wearable health devices don’t replace your annual physical, and you should always discuss any concerning info with your doctor before self-diagnosing.
Even better than using data retroactively, as I planned to do with my heart rate, is to discuss with your doctor ahead of time which metrics would be most helpful for you, and define the individual parameters to aim for, Tomey says.
[READ How to Protect Your Data When Using Health Tracking Apps]
What Wearable Devices Can Track
As the technology in our wearable devices becomes increasingly more advance, these small trackers can provide us with a wide range of health information, including:
— Steps and daily movement
— Heart rate
— Sleep
— Blood oxygen
— Workouts and cardio fitness
— Stress
— Recovery
Read on for guidelines of metrics to pay attention to, what the numbers mean, what’s “normal” and when to move from an app to an office.
Steps and Daily Movement
We’ve all heard of the ubiquitous “10,000 steps a day” goal, but achieving that number isn’t necessary if it’s not realistic for you.
A 2025 meta-analysis found that walking 7,000 steps is sufficient to improve health.
“Our focus should be on moving more,” Tomey says. “Ten thousand is great as an aspirational number, but it shouldn’t become a discouragement from moving more if unattainable.”
In other words, don’t let the perfect be the enemy of the good: Some walking is better than none.
Some wearables also count exercise minutes and repetitions of exercises, providing guidance during workouts to stay on target.
“However, current technology is limited in detecting proper mechanics or form,” says Vincent Luppino, a physical therapist at HSS.
The recommendation for adults from the American Heart Association is to get 150 minutes of exercise per week of moderate-intensity activity, or 75 minutes of vigorous activity.
Current guidelines for exercise minutes aren’t separated by sex, although some research suggests women need fewer exercise minutes than men.
The table below shows the steps per day and activity level you should aim for by age.
When to see a specialist
— Who to see: Physical therapist or sports medicine physician
— The red flags: If your movement is limited by persistent joint pain, sudden loss of balance or if you find yourself unable to hit even “sedentary” benchmarks (2,000 steps a day) due to exhaustion or pain, talk to your doctor.
“Pain is often the first signal that something isn’t functioning optimally,” Luppino says. “Normal aches and soreness are part of being active, but lingering pain
for days or weeks is a reason to seek medical evaluation.”
[SEE: Can Tracking Your Cortisol Help Your Health? Understanding the Stress Hormone]
Heart Rate
Wearables use photoplethysmography (PPG) to shine green LED light into your skin and measure the difference in light absorption as your blood pumps to count your heartbeats per minute.
A normal adult resting heart rate is between 60 and 100 beats per minute (BPM), with a lower rate indicating better physical fitness because your heart doesn’t have to work as hard to pump blood.
Women’s resting heart rates tend to be a little faster than men’s within this range because their hearts are smaller; for the same reason, children’s resting heart rates can be over 100 beats per minute.
Some wearables alert you if your heart rate is consistently too fast, too slow or beats irregularly.
Measuring your heart rate during exercise can also give you an indication whether to push yourself harder or not overdo it, which is how Luppino uses his.
“I personally use a wearable daily. I started mainly to track steps and log workouts, but now I use devices that measure physiological biomarkers (such as your heart rate) to guide training and recovery,” he says.
Use this formula to calculate your maximum heart rate:
Maximum heart rate = 220 — Your age
Your target heart rate should be:
— Moderate activity: 50-70% of your maximum heart rate
— Vigorous physical activity: 70-85%
The table below gives target HRs during exercise based on age.
When to see a specialist
— Who to see: Cardiologist or electrophysiologist
— The red flags: If your resting heart rate is consistently above 100 bpm, doesn’t drop back to normal quickly after exercise or you have “racing” or “fluttering” sensations (palpitations), talk to your doctor.
[READ: Keeping Track of Health Information: What You Should Know.]
Sleep
Some trackers are specifically used to assess sleep, but even those that measure multiple metrics can identify sleep patterns.
The amount of shut-eye you get is important, of course, but other metrics including the type of sleep and number of wakings are also critical in determining sleep quality.
Using accelerators and PPG to detect lack of movement and heart rate patterns, wearables create algorithms to estimate deep sleep, light sleep or REM sleep.
Some also track breathing patterns and blood oxygen levels.
“As artificial intelligence improves and datasets grow, these devices will increasingly provide actionable insights, including suggestions on when to consult a health care professional,” Luppino says.
Although they’re not as accurate as a professional sleep study, health trackers are useful for estimating how much sleep you should get per night. For those who don’t get enough sleep, this is a helpful feature.
When to see a specialist
— Who to see: Sleep medicine specialist or pulmonologist
— The red flags: If your tracker shows that you frequently wake up or experience gasping episodes, you feel exhausted despite getting enough sleep, or your blood oxygen level — also referred to as SpO2 — drops significantly during the night, you may have sleep apnea, so talk to your doctor about professional sleep testing.
Blood Oxygen (SpO2)
Wearables use LEDs to calculate SpO2, which is your blood oxygen level that indicates the amount of oxygen your lungs circulate in your blood
, by measuring how blood absorbs and reflects red and infrared light.
One reading won’t tell you much, but patterns over time yield useful data.
Although not as accurate as medical-grade pulse oximeters that go on your finger, health trackers provide a baseline blood oxygen level, so if you’re not feeling well and see it’s off, you can tell your doctor.
“Your body constantly strives to maintain balance, or homeostasis, and deviations in these biomarkers (such as SpO2) can indicate underlying issues,” Luppino says.
This metric is also useful for measuring your oxygen level when you’re sleeping to identify if you may have sleep apnea.
For adults and children, this table shows what’s normal and when to contact your doctor.
When to see a specialist
— Who to see: Sleep medicine specialist or pulmonologist
— The red flags: If your blood oxygen level is consistently under 95, particularly in conjunction with additional symptoms such as shortness of breath, blue lips or nails, chest pain or fast heart rate, talk to your doctor. Under 88 is a medical emergency.
Workouts and Cardio Fitness (VO2 Max)
VO2 max is the volume of the maximum amount of oxygen your body can take in and use.
Wearables use accelerometers, heart rate and GPS during a sustained workout, along with supplied info such as your age, sex and weight, to calculate VO2 max.
The higher the amount, the better your heart and lungs are working, and the more physically fit you are, which is why active people like Luppino use it to measure their fitness level during workouts.
“Having objective metrics allows me to make informed decisions to improve my health and performance,” Luppino says.
Monitoring your VO2 max can show how much progress you’re making in increasing the difficulty of your workouts.
Wearables don’t track VO2 max as well as monitoring in an exercise medicine lab, but can give you a baseline for your cardiorespiratory fitness and function.
When to see a specialist
— Who to see: Cardiologist
— The red flags: If your tracker shows a consistently low number, especially if you’re overweight or get easily winded, you may be at increased risk for cardiovascular disease. A cardiologist can give you a full workup and come up with a plan to improve your heart health.
Stress
Wearable technology has come so far, it’s now assessing our st
ress and recovery physiological states.
Advanced trackers analyze heart rate and another metric, heart rate variability, to identify when your nervous system is in “stress” or “rest” mode.
It may even alert you if it thinks you’re too mentally stressed and should do breathing exercises to calm down.
“Stress in life is a real phenomenon and of genuine importance to our health, including our cardiovascular health,” Tomey says. “To the extent that changes in variables measurable on tracking devices appropriately calls our attention to our stress, this is good.”
However, health trackers don’t tell you why you’re stressed or if it’s good or bad stress.
An elevated level could identify negative stress, like pressure or anxiety, but also positive experiences such as being excited, or having a lot of exercise or caffeine.
Because algorithms used differ between wearable brands, there aren’t generally recommended numbers yet or differences in age or sex.
However, using Garmin’s tech, their scores are:
When to see a specialist
— Who to see: Mental health professional
— The red flags: If your device constantly measures you in a stressful state, it’s worth examining the reasons behind it, as many of us don’t realize how psychologically stressed we are until we have physical symptoms.
Recovery
On the flip side, trackers can also monitor the times when your body is in rest and recovery mode, such as when you’re calm, inactive or sleeping, using resting HR, HRV and respiratory rate (breaths per minute).
Some trackers measure and suggest the amount of recovery time you need before your next workout by incorporating data about your fitness level, VO2 max and other proprietary metrics.
“I check my wearables to see if I need additional rest after intense workouts or illness,” Luppino says.
Although each tracker has its own algorithms, one consistent number to assess general fitness is your heart rate recovery, which measures the difference between heart rate at peak intensity and at a set time after stopping.
A quicker recovery time is linked to better fitness, while a slower recovery indicates an increased risk for cardiovascular disease.
To calculate your recovery score, use the following formula:
Recovery number = Peak heart rate — Resting heart rate at 1 minute post-exercise
Although this metric can be measured in varying ways, a generally accepted good recovery number to aim for after 1 minute of rest is 18 beats or higher.
When to see a specialist
— Who to see: Cardiologist
— The red flags: If your device is consistently giving a high heart rate recovery even after establishing an exercise routine, you may want to consult a cardiologist to have an exercise stress test.
Bottom Line
Fitness trackers can provide users with useful data for improving general health, but any concerning results should be followed up with a doctor before any diagnosis can be made.
Wearable technology is improving, but take results with a grain of salt.
“While we’re not fully there yet, I see a future for a hybrid approach in which wearables handle data collection and clinicians interpret it for individualized care,” Luppino says.
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How to Use Your Wearable Health Data originally appeared on usnews.com