Reality check... HRM vs. Treadmill Calories Burned

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  • csch79
    csch79 Posts: 37 Member
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    I have the opposite problem. I just purchased a Polar FT7. I always knew the calories on the treadmill were exaggerated so I never paid attention to them.

    I've worked out twice with the new HRM monitor and both times the calories on the HRM are a lot higher than the machine display. Last night the Life Fitness treadmill stated that I had burned 403 calories. The HRM stated that I had burned 600. It was very similar the previous day. It is funny because I was fully expecting the HRM to tell me I had only burned about 300-350 and I would have been fine with that. Now I'm second guessing it. If I really did burn 600 calories in 53 minutes then I am very pleased.

    The gym has a couple different types of treadmills so I may try one of the other styles just to see what it's calculator says.
  • Gilbrod
    Gilbrod Posts: 1,216 Member
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    That's what I use. When I use a Polar treadmill at my gym, it syncs my heart rate with the machine. But the calories on the treadmill are about 120 less than what the HRM says. It's never accurate. But a good guesstimate.
  • Richard170
    Richard170 Posts: 37
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    I have been thinking about getting a HRM and I have been thinking about the accuracy issue with estimating calories burned using a HRM. At the office, we have a bike and a treadmill, both of which calculate calories, but I must work a lot harder on the treadmill to get the same numbers as on the bike. The treadmill is just making an estimate because two different people, one heavy and one light, will do significantly different amounts of work walking up the same incline over the same distance.

    Work is the amount of energy transferred by a force acting through a distance. The common unit for expressing work is the joule which is a force of one newton over a distance of one meter. A treadmill knows how far you have walked and at what incline but it does not know your mass, at least not the one I use at the office, so it can not accurately calculate the work you have done. A calorie is about 4.2 joules. Dietary calories are really kilo-calories so 1 dietary calorie is about 4.2 kJ.

    W = F * d

    An exercise bike knows both how many revolutions you have peddled ( the distance) and how much force was used and can easily, and accurately calculate calories expended during a workout, at least if it is not a pile of junk. It can also accurately calculate the rate of work performed (Power W = PT ) which is commonly displayed in Watts with 1 watt equal to one joule per second.

    If you want to have an idea how accurate a HRM is at estimating calories burned in a workout, I would get on an exercise bike and compare results. From this, it would not be at all difficulty to calculate a factor to be used to adjust a HRM estimated calories so that you can more accurately record your caloric expenditures.
  • evesacks
    evesacks Posts: 94 Member
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    A good rule of thumb with running / jogging is 1 mile = 100 calories.

    I borrowed a kifit (which calculates calories more accurately than a HRM (pulse/pedometer/temperature/sweat and motion) and it was consistent with the 1 mile = 100 calories.

    Its only a problem if you plan to eat all your exercise calories.
  • HMonsterX
    HMonsterX Posts: 3,000 Member
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    My HRM should be here in a few days, and i cant wait to try it and compare things.

    I never believe what MFP says for my calories burned, especially as my sports are kinda hard to judge calorie burn (Badminton and Tenpin Bowling competitive). For badminton competitive, does it mean singles or doubles? Does it take into account the time between games, between points? Easy or hard game? Im already halving the value MFP gives my badminton sessions, and im expecting my HRM to say its even less, but at least them ill know for sure.

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