HR Discrepancies while cycling

slinx Registered Users Posts: 3
Apprentice Traveler
edited January 24 in TomTom Sports
howzit guys. so i use my TT runner 3 watch for workouts on an indoor trainer and just recently noticed something which i need some clarity on. while sitting and pedalling with my hands on the bar the hr reading on my watch matches what my hr "feels like" ( lets say somewhere between 150-160pbm) but if i stand up out of the saddle and pedal with my hands still on the bar i notice my hr drops all the way down to about 120-130 yet it feels like my heart rate is screaming.

is it possible that the height or position of your wrist in relation to you heart, ie higher or lower than the height of your heart, affects the heart rate reading on your watch and does not accurately display your current heart rate?


  • tfarabaugh
    tfarabaugh Posts: 16,938
    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. Based on numerous tests I have performed, I find that with weight training it is generally 5%-7% lower based on the wrist than the chest, so if I do not use the strap I just adjust accordingly.

    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.
  • slinx
    slinx Registered Users Posts: 3
    Apprentice Traveler
    that does makes sense and sufficiently answers my question.