Heart Rate Monitors with VERY different results

CathyMW813
CathyMW813 Posts: 23 Member
in Fitness and Exercise
My husband and I worked out together this weekend and did the exact same routine--one that my trainer gave me to try. Intervals on the stair climber interspersed with various exercises (lunges, squats, tricep dips, etc). We started and stopped our respective heart monitors at the same time. He has a Timex and I have a Polar FT7. When we were done, my monitor said 350 or so calories burned and his said around 700! I was expecting SOME difference--he is 5 years younger and he is very lean. And I am not--yet! That just seems like such a huge difference in calories burned. Is one of our monitors "off" or is that much of a difference normal?

Replies

  • SJ46
    SJ46 Posts: 407 Member
    Totally possible - you are different sizes, no? different fitness levels? working at different levels during the workout? different weights for the strength work?
  • 3dogsrunning
    3dogsrunning Posts: 27,167 Member
    HRMs are still estimates. They also aren't accurate for anything but steady state cardio sessions. And each brand may have different formulas.
    Does your husband weigh more than you?
    Also, the more fit you are, the more inaccurate a HRM can be unless you set it up properly (if it can be set up differently).

    A good read
    http://www.myfitnesspal.com/topics/show/773451-is-my-hrm-giving-me-incorrect-calorie-burn
  • heybales
    heybales Posts: 18,842 Member
    Timex has terrible calorie burn formula's they use, Polar and Garmin with Firstbeat algorithms and Suunto are best.

    And even if you both had FT7's on, would be very different results, as it is basing it's math on your BMI and some assumptions (worse BMI less fit you are), and your HR could have been totally different, your genetic and exercise maintained HRmax may be very different, ect.

    So both of you are probably off by 30-50% easily. Which direction? Who knows.

    http://www.myfitnesspal.com/topics/show/774337-how-to-test-hrm-for-how-accurate-calorie-burn-is

    Also, problem for your specific workout.

    The formula's for calorie burn the HRM's are using are ONLY valid for steady-state (3-5 min same HR) aerobic exercise from about 90 to about 150-160 (anaerobic threshold).

    Intervals and strength training is anaerobic and non-steady-state - so totally inflated for both of you.
    So is wearing it all day in case that comes to mind.
  • CathyMW813
    CathyMW813 Posts: 23 Member
    We did the same weights for the strength work and both did the same amounts of time on the stair-climber (I actually did a higher resistance on that). His HR average was around 10-15 higher than mine. He weighs less than I do and doesn't have alot of body fat. I was expecting SOME difference, just not that much. I want my calories burned to be higher--like his!

    I'll check out that article. Thanks.
  • heybales
    heybales Posts: 18,842 Member
    For you and that HRM, you can get a much better estimate than even he is getting from his Polar.

    Here is a Polar funded study formula, and info on estimating your best HRmax stat, and VO2max stat, and after plugging in other stats HRM would use, you get your own personal calorie burn table.

    HRM tab in the spreadsheet linked in this post.

    http://www.myfitnesspal.com/topics/show/813720-spreadsheet-bmr-tdee-deficit-macro-calcs-hrm-zones

    Stats at top you know.
    Section on VO2max to figure it out.
    Section on HRmax to estimate it.
    Fill in stats at top with those estimates.
    Go to bottom of page, fill in time spent and averageHR during the session - there is your best estimate of calories burned. Tweaked better than most Polar's would give you.

    And you and hubby can compare what happens even if you kept the HR the same.

    Just use the instructions at top of Simple Setup tab for making your own copy of the spreadsheet.

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