You laced up, started a run on your Apple Watch SE (2nd generation), and finished to find no heart rate, missing distance, or a workout that never seemed to record at all.
It is one of the more frustrating watch problems because you only notice after the effort is already done. The good news is that this model has all the hardware it needs to track exercise, so most cases come down to fit, settings, or software rather than a broken sensor.
The SE (2nd generation) tracks workouts using a second-generation optical heart sensor, a high-g accelerometer, a high dynamic range gyroscope, built-in GPS (L1 GPS/GNSS/Galileo/QZSS), a compass, and an always-on altimeter, all paired to an iPhone running the Apple Watch app.
The 10 fixes below are ordered from the quickest and safest to the more involved, ending with the official reset and support path. Work through them in order and most tracking problems clear up well before the end of the list.
Start With How the Watch Sits on Your Wrist
Before you touch a single setting, check the fit, because a loose or low band is one of the most common reasons heart rate and workout data do not record. The watch must sit snugly on top of your wrist so the optical heart sensor stays close to your skin. According to Apple, you might want to tighten your Apple Watch band for workouts, then loosen it when you are done.
Movement type matters too. Rhythmic activities such as running and cycling give better heart-rate results than irregular movements like tennis or boxing. Cold weather can lower skin perfusion and some tattoos can block the sensor's light, so if readings are spotty in those conditions, the fit and skin-contact step is doing more work than you might expect.
Make Sure You Are Starting the Workout the Right Way
If a session never seems to record, the cause is sometimes how it was started or how it ended. Picking the workout that matches what you are actually doing, for example Indoor Run on a treadmill, helps the watch track correctly with the right sensor mix.
Open the Workout app on your Apple Watch. Next, turn the Digital Crown to the workout you want. Tap the Play button, or tap the center of the screen, to begin.
To pause without accidentally ending a session you think is still recording, press the side button and the Digital Crown at the same time. Ending instead of pausing is an easy mistake mid-workout, so get familiar with that pause combination.
Confirm Wrist Detection Is Turned On
Wrist Detection has a direct effect on activity tracking. If it is off, your watch cannot track your Stand progress and you will not get Stand notifications. It is on by default, but it is worth confirming. On your iPhone, open the Watch app, go to the My Watch tab, tap Passcode, and make sure Wrist Detection is on.
Turn On Fitness Tracking in the Health App
If steps, workouts, or other data simply are not recording, the privacy setting that authorizes tracking may be switched off. This is worth checking after a software change or a new setup.
On your iPhone, open the Health app. Tap your profile. Tap Devices, then tap your Apple Watch.
Tap Privacy Settings. Turn on Fitness Tracking. With Fitness Tracking enabled, steps and other workout information can be recorded. If this was off, it alone can explain a watch that appeared to track nothing at all.
Enter Accurate Personal Information
Your watch uses your height, weight, gender, and age to calculate calories and other workout measurements, so wrong or missing details lead to inaccurate tracking even when the sensors work fine. If your calorie numbers look off, start here.
On your iPhone, open the Watch app, go to the My Watch tab, tap Health, then Health Details, then Edit, and update each item. Correcting these figures often fixes calorie and activity readings that seemed broken but were really just miscalculated.
Turn On Location Services and Calibrate the Watch
GPS-based distance, pace, and calibration all depend on two iPhone settings. If outdoor distance or pace is missing, these are usually why.
On your iPhone, go to Settings. Tap Privacy & Security. Tap Location Services and make sure it is on.
Scroll down to System Services and make sure Motion Calibration & Distance is on. With both enabled, the watch can use your phone's location data and motion calibration to record accurate distance and pace, and to feed the calibration process.
To calibrate, wear the watch and go to a flat, open outdoor area with good GPS reception. Open the Workout app and tap Outdoor Walk or Outdoor Run, then walk or run at your normal pace for about 20 minutes. Calibration improves the accuracy of distance, pace, and calorie measurements and helps the watch learn your stride for situations where GPS is limited.
If distance or calorie tracking is consistently off even after you calibrate, the watch may be working from stale calibration data. On your iPhone, open the Watch app, go to the My Watch tab, tap Privacy, then tap Reset Fitness Calibration Data. After resetting, recalibrate with another 20-minute outdoor walk or run.
Restart the Watch, and Force Restart It If It Is Frozen
A watch that has quietly stopped tracking often just needs a restart. Start with a normal restart, and only force restart if the watch is unresponsive.
To restart normally, press and hold the side button until the sliders appear, tap the Power Button, then drag the Power Off slider to the right. To turn it back on, hold down the side button until the Apple logo appears.
If the watch is unresponsive and not tracking, force restart it. Hold down the side button and the Digital Crown at the same time for at least 10 seconds, until the Apple logo appears. This recovers a frozen watch without erasing any of your data.
Update watchOS and Your iPhone
Outdated software can cause tracking bugs, so keeping both devices current is a low-effort fix that resolves a surprising number of problems. The SE (2nd generation) runs watchOS 9 or later and does not support watchOS 26, so install the latest version it offers.
You can update on the watch itself or from your iPhone. On the watch, open the Settings app, then go to General > Software Update, and tap Download and Install if available.
On the iPhone, open the Apple Watch app, then go to My Watch > General > Software Update > Download and Install. For the update to complete cleanly, keep the watch on its charger and at least 50% charged, and keep the iPhone on Wi-Fi and nearby.
Try an External Heart Rate Monitor If Readings Will Not Settle
When skin perfusion, tattoos, or irregular motion keep the wrist sensor from getting a consistent reading, you do not have to rely on the optical sensor alone.
You can connect the Apple Watch wirelessly to external heart rate monitors such as Bluetooth chest straps. This is a practical workaround for high-intensity or cold-weather sessions where the wrist sensor struggles, and it lets the watch keep recording reliable heart-rate data throughout the workout.
Unpair, Erase, and Re-Pair as a Last Resort
If none of the above works, unpairing and re-pairing is the final software fix to try before considering hardware service. Before you start, know what happens to your data. Unpairing restores the watch to factory settings and removes Activation Lock, but your iPhone automatically backs up the watch before it unpairs, so you can choose Restore from Backup when you set it up again.
- 1.Keep your watch and iPhone close together.
- 2.On your iPhone, open the Apple Watch app.
- 3.Go to the My Watch tab, then tap All Watches.
- 4.Tap the info button next to your watch.
- 5.Tap Unpair Apple Watch and confirm.
- 6.Enter your Apple Account password to disable Activation Lock, then tap Unpair.
Once it finishes, set the watch up again and choose Restore from Backup so your history and calibration come back. If tracking still fails after re-pairing, it may be a hardware issue, and the next step is to contact Apple Support.
Frequently Asked Questions
Does the Apple Watch SE (2nd generation) actually track workouts?
Yes. It has a second-generation optical heart sensor, a high-g accelerometer, a high dynamic range gyroscope, built-in GPS, a compass, and an always-on altimeter, and it runs the Workout and Activity apps. Workout heart rate, calories, distance, and pace are tracked through the optical heart sensor, accelerometer, and GPS.
Why are my heart-rate readings dropping out during exercise?
The most common reason is fit. The watch must sit snugly on top of your wrist so the optical sensor stays close to your skin, and you may want to tighten the band for workouts. Irregular movements like tennis or boxing, cold weather, and some tattoos can also interfere with readings, and a Bluetooth chest strap is a reliable alternative in those cases.
Will updating erase my workout data?
No. A software update keeps your data. The action that resets the watch to factory settings is unpairing or Erase All Content and Settings, and even then your iPhone backs up the watch before unpairing so you can restore it.
What watchOS version should my SE (2nd generation) be running?
It runs watchOS 9 or later and does not support watchOS 26, so install the latest version your watch offers. To check, open Settings on the watch and go to General > Software Update, or use the Apple Watch app on your iPhone under My Watch > General > Software Update.
What should I do if tracking still fails after re-pairing?
If you have worked through fit, settings, calibration, a restart, a software update, and a full unpair and re-pair, and tracking still does not work, it may be a hardware issue. At that point, contact Apple Support for service.