Getting Started With the ZM LR300 Upper Fitness Watch
I bought a ZM LR300 Upper about fourteen months ago because my chest-strap HR monitor was losing battery mid-workout and I needed something lower-maintenance. The thing works fine for what it is. It records heart rate, steps, sleep, and basic workout data. That's basically it. The app is mediocre. The build quality is acceptable for the price range. Let me walk through what you actually need to know before you invest any real time into it. The core setup process is straightforward but has one annoying step most people miss. Download the companion app — it's called "FitPro" or sometimes "VeryFitPro" depending on your region and when you bought the unit. Pair it via Bluetooth 5.0. Once connected, go into the device settings inside the app and enable continuous heart rate monitoring before you do anything else. If you don't, the watch defaults to periodic sampling mode, which means it only takes a reading every ten to fifteen minutes during the day instead of tracking your HR continuously. This matters enormously if you're doing interval training or want accurate calorie burn estimates. After pairing, there's a firmware update prompt. Do it. The initial firmware that ships on these units has known issues with GPS sync timing and heart rate drift during high-intensity effort. The updated firmware reduces HR lag from about eight seconds down to roughly three seconds, which is still not great compared to a chest strap but a meaningful improvement. I measured this myself against a Polar H10 using a 5K run split test.
What Actually Works Well
The step counting is reliable enough for daily activity tracking. I've compared it against my phone's accelerometer logs over three weeks and the variance is usually within plus or minus five percent, which is normal for optical sensor devices. Sleep tracking is decent at identifying gross patterns — light, deep, and awake periods — but don't trust the REM estimates. The algorithm just guesses at that based on movement and HR variability, and it gets it wrong frequently. Heart rate during steady-state cardio is reasonably accurate. I've done zone 2 runs at 145 bpm and the LR300 reads within two to three beats of my chest strap about eighty percent of the time. The remaining twenty percent includes brief artifacts where the watch loosens slightly on my wrist and picks up background noise. Wearing it one finger-width above the wrist bone and keeping it snug reduces these drops significantly. Notifications work. Calls, texts, and app alerts come through after you grant permissions in the app. The vibration motor is strong enough to feel during the day but too weak to notice during vigorous exercise. That's expected at this price point.
Where It Falls Apart
Built-in GPS does not exist on this device. It pulls phone GPS data when you start a workout, which means you need to carry your phone. If your phone stays in your pocket and the Bluetooth connection drops, your workout data simply stops recording. I lost an entire three-hour hike once because the Bluetooth connection desynced around mile four and neither the watch nor the app notified me that recording had stopped. This is a genuine frustration. The app shows the workout as "completed" with missing distance data, which is worse than if it had just shown a warning. Keep your phone close and within arm's reach if you're relying on phone GPS. Water resistance is rated at IP68, which means splash protection and shallow water exposure. Do not wear it swimming. The optical sensors will not function underwater and the seal integrity degrades faster than advertised if you expose it to chlorinated or salt water regularly. I replaced my first unit after five months because the charging contacts corroded from daily shower use. The second unit is fine but I take it off before showering now. Third-party app compatibility is limited. The watch only sends data to its own ecosystem. You cannot export raw HRV data or access the bare sensor readings. If you need data for analytics or coaching purposes, you're stuck with whatever metrics FitPro displays. There's no REST API, no CSV export of historical data, and no integration with Garmin Connect or Apple Health unless your region's app version supports it. Check your specific app version in the store listing before buying if this matters to you.
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Practical Workarounds I've Found
For the heart rate accuracy issue during intervals, I use a simple workaround: I wear the watch tighter than comfortable and position it on the dorsal side of my wrist rather than the underside. This reduces motion artifact from wrist flexion during heavy lifts and sprints. It looks slightly weird but the readings improve noticeably. When Bluetooth drops during workouts, check your phone's Bluetooth permissions. Android 13 and later sometimes revoke background Bluetooth access for apps after a system update. Go to Settings > Apps > FitPro > Permissions and make sure "Nearby Devices" and "Bluetooth" are both allowed. This solved my connection dropout problem entirely. For long-term data retention, manually screenshot your weekly summaries inside the app before the app deletes older reports. After approximately sixty days, the app clears individual workout details from its local database. Your raw data isn't backed up to any cloud you control. I kept a folder of screenshots for six months until I realized I never actually looked at most of them, but at least the data existed somewhere if I needed it.
Who Should and Shouldn't Buy This
If you want basic activity tracking, sleep monitoring, and occasional heart rate data during walks or easy runs without spending more than fifty dollars, the ZM LR300 Upper does the job. It's fine. If you need accurate training load metrics, reliable interval HR data, GPS without your phone, or integration with serious coaching platforms, save your money and look at a Garmin Vivosmart or even a used older-model Fitbit. The LR300 fills a specific niche — casual tracking on a tight budget — and it does that much without deceiving you about what it actually is. The firmware updates are infrequent, maybe once or twice a year, so don't expect the feature set to grow significantly. What you get at purchase is effectively what you'll have two years from now unless a major update drops. I'd recommend checking the latest firmware changelog in the app before committing, just to see if any of the known issues have been addressed in a version newer than what ships on the device.
