Weight training with Spark 3 Cardio

Memphis732 Registered Users Posts: 1
New Traveler
edited January 24 in TomTom Sports
Hi all,
How does everyone track calories burnt while weight trianing?
I'm fairly new to the watch and have just done a weight training session and thought i would use the 'gym' mode, i did 43 mins in the gym doing fairly intensive workout and apparently i have burnt 351 kcal, which makes me feel great (or at least it would if that was right, i would guess around half that)
So how can i track this properly and what is the gym mode for?


  • tfarabaugh
    tfarabaugh Posts: 16,938
    In gym and freestyle mode it is using your HR to calculate calories applying a fairly standard HR based calculation taking into account weight, age and gender. How accurate the calories are depends on how accurate the HR readings are, and how well the watch is collecting them along with the exercises being done. All sports watch calorie algorithms assume you are doing aerobic activities using multiple muscle groups like aerobics or running or cycling. Strength training exercise is primarily anaerobic. You are woken single muscle groups in an anaerobic manner, so the Hr does not correlate tpo calories burned like it does for aerobic exercise. The elevated HR is due to pressure from pushing that single muscle, not from increased energy usage throughout the body, so sports watches are going to naturally over count calories during weight lifting because of this.

    There is an issues around heart rate using optical HR monitors for weight training, and this are on all devices, not just TT ones: low heart rate caused by forearm muscle tension and flexion. 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. Plus bear in mind the reading from the wrist or the strap is likely incorrect due to it not being an aerobic activity.

    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.