Inaccurate reading on heart rate

muscle123 Registered Users Posts: 1
New Traveler
edited January 24 in TomTom Sports
When using my Max Trainer 5 and my Tom Tom watch today, I noticed my Tom Tom watch started displaying a decreasing heart rate from 145bpm to 90bpm which was really frustrating and seemed be incorrect because I was working really hard in the fat burn zone. Has anyone had issues with Heart Rate accuracy?


  • tfarabaugh
    tfarabaugh Posts: 16,943
    There are two issues around heart rate using optical HR monitors, and these are on all devices, not just TT ones: low heart rate and HR spikes. Low HR is often seen in rowing, cycling and weight lifting. Any time you do an activity that squeezes or tenses the forearms (like the pull stroke in rowing, bearing down on your handlebars in cycling, or virtually any weight lifting move) you are squeezing the blood vessels the watch is reading, so it sees this as a reduced pulse. It is not that the watch is having a problem reading your pulse; it is that your pulse at the wrist has dropped because you are temporarily cutting off blood flow to the vessels it is reading. Depending on how you are gripping the Max Trainer this may be the cause. I would suggest trying to keep a looser grip and keep your wrists straight. I have experienced this with every optical HR I have used, including a Mio and a Scosche unit. For these sorts of activities, you are better off using a chest strap synced to the watch if getting a more exact reading is important to you.

    I hope this helps answer your question. If so, please mark it as a solution so others can look for it if they have the same question.