27. July 2025 by Roy
When you're hitting the pavement or trail, your sports watch or smartphone is your digital training partner — tracking your pace, distance, heart rate, and more. But if you've ever looked at your run data and thought, "There’s no way I ran through that lake," or seen suspiciously high or low heart rate during parts of your activity, you’re not alone.
Here’s how to ensure you get the most accurate GPS and heart rate monitoring data for your workout, whether you're using a dedicated sports watch or your mobile phone.
Don’t press “Start” as soon as you step outside. Give your device 10–60 seconds to lock onto a strong satellite signal — especially if you're using a GPS watch. Most devices will indicate GPS strength (like bars or a "GPS ready" message). If you're using a phone, make sure location services are enabled and consider changing settings to "High Accuracy" mode.
Tall buildings, dense forests, and even heavy cloud cover can interfere with satellite signals. Try to start your run in an open area if possible. If you're running in a city or on a trail with dense canopy, expect some margin of error in your GPS track.
Wearing your sports watch on your wrist is fine, but make sure the antenna (typically in the face of the watch) isn’t obstructed by your sleeve. If using a phone, carry it in an armband or waist belt, not deep in a backpack or under layers of clothing.
And, yes, GPS works really bad when submerged in water. So if you want to track distance while swimming outside you may want to put your watch inside your swimming head cap or on your buoy if you are using that.
Some newer watches offer access to multiple satellite systems (GPS, GLONASS, Galileo) or dual-band support. Enable these for better accuracy, especially in challenging environments. Keep in mind, it may reduce battery life slightly. Just keep in mind that this will use more battery.
For wrist-based heart rate sensors, a snug (but not too tight) fit is key. The watch should sit just above the wrist bone, flush against the skin. If it moves around while you run, data can be thrown off.
Cold skin and poor circulation can lead to inaccurate early readings. A short warm-up or wearing the watch during your pre-run prep can help stabilize heart rate readings before you start.
Sweat, sunscreen, or skin oils can interfere with the sensor. Clean the back of your watch regularly with a damp cloth and make sure your skin is dry and clean before a run.
If precise heart rate data is critical (e.g., for interval training or heart rate zone training), a chest strap is still more accurate than wrist-based monitors — especially during high-intensity efforts or activities with lots of arm movement.
No device is perfect, but with a few habits and tweaks, you can dramatically improve the quality of your training data. Whether you're training for a race or just tracking progress, accurate metrics help you train smarter and stay motivated.
For any workout it is also important to start your session with a meaningful activity type. For example, if you are about to head out for a tempo run be sure not to start your sports watch with walking or hiking as the activ ity type as those activities will result in less frequent data measurements. For running you typically want your watch to record data every second, so select running as the activity type.
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Good luck on your journey.