In Praise of the Much Maligned Heart Rate Monitor

fyoung1111
fyoung1111 Posts: 109 Member
I started wearing one because I was so out of shape that a 100 meter trot at a slow pace would put me dangerously over my theoretical heart rate limit. I kept wearing one because it was a great, simple way to get back into shape—jog until I hit my limit; walk until I was 25% under my limit; rinse and repeat as long as I had time to do it.

Then one glorious day I jogged and jogged, and jogged and never hit my limit. Had to jog faster, and faster and faster just to get close.

It’s a great, simple training tool. It’s both reassuring (I’m not about to die) and motivating (I’m not pushing nearly hard enough).

But jogging is boring. It’s also hard on an aging frame. Variety is the spice of life. Throw in some cycling. Add a little inline skating. How about some kayaking when it’s not blowing too hard?

Now I’m more concerned with shedding pounds than getting into shape but my Fitbit activity tracker only understands how to convert STEPS into calorie expenditure numbers and my new, old frame friendly, alternative cardiovascular exercise don’t involve steps.

What to do? Upgrade my activity tracker and strap the heart rate monitor back on when I’m not running or walking for exercise. The problem is that almost all activity trackers (Fitbit, Fuelband, UP24, Pulse, Shine) understand steps and can sometimes differentiate between walking and running. They equate steps with calorie expenditure. If you aren't stepping you might as well be sleeping as far as they are concerned. That’s way better than nothing for 90% of us but I’m not one of them.

Cycling is the best mainstream example of this problem. I recently did an experiment where I rode the same 23K course two times in about one hour each time. My average heart rate was about 130 on each trip (OK I was dogging it). On the first run, my top-of-the line Garmin Vivofit was linked to my heart rate monitor. It recorded 629 steps I never took and credited me with 580 calories burned. On the second run (after a bowl of chili, three cupcakes and a nap) I left my HRM at home. That time VF recorded 879 nonexistent steps and awarded me with 107 calories which is barely more than I would have burned if I had been reading a book about cupcakes instead of blazing around Alameda like a comet on my orange bike.

Simple message—without the HRM, no steps = no calorie credit—HRM on board, make your heart hum and get the credit you deserve whether you are riding an orange bike or a red bull.

By the way, yesterday I did a similar experiment running a matched pair of 5K RUNS (think step-based) With HRM—5,015 Steps, 416 Calories. Without HRM—4,993 steps, 422 calories. Might as well have left the HRM hanging in the shower.

Hope this helps somebody.

Replies

  • ann121212
    ann121212 Posts: 290 Member
    I did a similar test today only with walking. I mapped a 2.5klm course and walked it 4 times.

    Brisk walk no hrm - 85 calories
    Brisk walk with hrm - 136 calories

    Normal walk no hrm - 98
    Normal walk with hrm - 146

    I KNOW vivofit underestimates my distance (have measured it numerous times) - it looks like they also underestimate my calories. Perhaps if I was average height (instead of very short) their estimations would be closer to the mark.

    With the normal walk it took longer to cover the distance so there will be slightly more brm included in the total. Also the normal walk took more steps, my brisk walking stride is longer (hence less steps). My vivofit band registers 1 calorie per minute (approx) - I have heard average people register 1 calorie per 30 seconds (sigh another reason to hate being short).

    The course was flat - and flat walking makes very little difference to my heart rate (add a few big hills and i can get it to climb rapidly) - average hr brisk walk was 107 - average hr normal walk 105.

    Outcome - I will not be using the hrm for walking based exercise unless it involves hill climbs or weight bearing elements.

    PS I used pen and paper and recorded all my readings from my vivofit immediately prior to starting and immediately after finishing.
  • fyoung1111
    fyoung1111 Posts: 109 Member
    Lots of surprises here.

    1. You are getting a nearly 50% bounce in calories for using the HRM for walking; and

    2. You are burning more calories on an normal than a brisk walk. Doesn't seem likely that there was more than an 8 minute difference in the times? Less steps for brisk makes sense. Most people increase speed with a combination of cadence and step length within any given gait.

    3. That is a pretty negligible change in heart rate between Brisk and Normal. Do yo have an estimate of your speed for each?

    4. That you are going to eschew your HRM for walking when it aparently gives you a substantially higher burn than without. Most experts agree that HR based calorie expenditure estimation trumps all other methods except full on VO2 Max facemask and all.
  • ann121212
    ann121212 Posts: 290 Member
    I was also surprised with the results.

    I immediately decided to redo them in a more controlled environment (I was using a meandering walkway around a lake, lots of people, dogs, and bikes). Ideally I would like a 1klm, straight, flat, paved area - preferably a bit private (so I dont look like an idiot marching up and down :laugh: )

    I have read articles over the years that say walking 5klm burns only slightly different calories that running it does. You are moving a set weight over a set distance with the only difference being the time frame.

    I am not really concerned about recording exact calorie burn on mfp (I would really love it to be correct, but a reliable average is acceptable). The convenience of heading out the door for a quick 20 walk whenever time/inclination allows outweighs the fuss of using the hrm - UNLESS it is a long/difficult walk. I am nearing the end of my weight loss journey and am no longer paranoid about calorie numbers, I just like playing with the numbers themselves :happy:

    I will write up the results of the next experiment when completed.
  • fyoung1111
    fyoung1111 Posts: 109 Member
    Thank you.

    On the subject of walking vs. running:

    1. Walking is ALL good. There may be no better exercise in the world.

    2. If you are in a hurry and/or have a LOT of ingested calories to dispense with, running is hard to beat.

    Walking at 3MPH is worth 3.5X your resting metabolic rate / hour

    Running at 6MPH is worth 9.8X your resting metabolic rate / hour

    A 70kg person would burn up an extra 175 Cal by walking 3 miles.

    The same person would burn an extra 308 Cal by running the same distance in half the time.

    The walker probably got their HR up to 100.

    The runner got their HR up to 150. The runner's knees hurt :(.

    We all just need to know what tools are available to us.
  • ann121212
    ann121212 Posts: 290 Member
    Thank you, I trust your figures more than the ones I have read over time (on different weight loss sites) - owing to your love of numbers i imagine you have researched them :happy:

    When time allows I will cross check your numbers with my vivofit and hrm - I would guess that those figures are for average fitness people of average height - I wonder what difference there would be for short, unfit runners, but superfit walkers. I know from my early experiments with cycling my hr was through the roof, but quickly came down (also calorie burn).
  • fyoung1111
    fyoung1111 Posts: 109 Member
    Hey, it's all guesses. The best we can do is find the most thoroughly researched, science-based guesses. My numbers came from this document http://juststand.org/portals/3/literature/compendium-of-physical-activities.pdf but before you dive into that (which is endlessly entertaining) I suggest you get a head start here: http://en.wikipedia.org/wiki/Metabolic_equivalent.

    I find these pretty useful just to gauge whether or not the numbers I get off of my devices are even in the right ballpark. Also, METS are stated only in terms of calories/kg/hour so one size fits all. In other words, you and I would burn the same METS walking 3mph but I, being heavier than you, would burn more calories. I'm currently 72 kg and so would burn 252 calories per hour (3.5 X 72) walking 3 mph. This includes my RMR of 72 (1X).
  • ann121212
    ann121212 Posts: 290 Member
    :happy: YUM! Sounds good.
  • fyoung1111
    fyoung1111 Posts: 109 Member
    I have been operating under the misimpression that the Vivofit established a serially monogamous relationship with each of my HRMs and have been carefully going through the process of PAIRing them when I switched from one to another.

    On Saturday I took a walk with another Vivofitter who was also wearing a HRM3. My Vivofit was displaying her HR. Turns out that Vivofits are opportunistic polygamists and will pair with the first Ant+ HRM they “see”. PAIRing, in the Vivofit world, only pertains to your Ant stick and BLE mobile devices.

    The upshot of all of this is that, if you are going to exercise in an Ant+ crowd, link your band and HRM at a distance from the crowd. Josh in Garmin customer support was pretty certain that your Vivofit would not link to a different HRM in the middle of an activity but I will be testing that theory.
  • ann121212
    ann121212 Posts: 290 Member
    I suppose it does make sense - your male vivo goes looking for a female hrm - where do you think little vivofits come from?:wink:
  • fyoung1111
    fyoung1111 Posts: 109 Member
    I've gotten a little more clarity on this subject from Garmin. Your Vivofit first looks for the HRM it paired with last. Failing to find that, it goes shopping for the strongest Ant+ signal it can find and pairs with that.

    AnnMareee my Vivofit is female and little Vivofits come from a farm in China.