My TomTom Spark 3 cardio doesn't record the right BPM

Thomas needs help
Thomas needs help Registered Users Posts: 2
Apprentice Traveler
edited January 24 in TomTom Sports
When i am out cycling my tomtom spark 3 is recording my pulse. It gives a very low average of 100 bpm, which should be close to double as i have heard. Its really weird, and i think it has influence on the calorie count. I drove 15,41 km on my bicycle. The route took 40 munutes, and my device said it was 291 calories. Whrn my brother took a 70 minute route on his bicycle his spark 3 (not cardio) recorded the calories to 997. That is over triple the calories my watch said on a route thats not even double as long.
I just think its weird, and i hope theres a solution for the problem.

- Thomas


  • tfarabaugh
    tfarabaugh Posts: 16,948
    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 actually dropped because you are temporarily cutting off blood flow to the vessels it is reading. 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. The calories should not be impacted if you were using it in cycling mode as that does not factor your HR into the calcualtions, it uses METs values based on pace.

    I hope this helped answer your question. If so, please mark it as a solution so others can look for it if they have the same question.
  • Thomas needs help
    Thomas needs help Registered Users Posts: 2
    Apprentice Traveler
    Thanks. But can there be any other reason that the calories are so low, because i don't know if i can trust it.