Wednesday, October 2, 2013

Exercise Estimates - Trying to be Truthful

As I exercise, I get quite a bit of feedback. My machines give me an estimate, my Fitbit has a calculation, my heart rate monitor comes up with another number. At times, I'll even check an internet calculator for an online opinion. Occasionally (but rarely) these numbers are similar, and then I feel fairly confident that the calorie burn is close to correct. But other times ... HUGE variations between the different devices. I've been getting a lot on inconsistent readings from my bike workouts especially.  

First, Fitbit (I LOVE LOVE LOVE my Fitbit, check out my post Wondering about a Fitbit ). Now, the Fitbit should be worn on the torso or waist (wrist only for sleeping, or if you have a Flex). Wearing it on my sock, while biking is NOT how it was intended to be used for an accurate calorie or distance/step count.  I was really only looking at Fitbit's numbers out of curiosity, but it's a good thing I didn't default and assume it was correct ...

So you can see, I have two activities recorded this day. The first was a 1.5 mile jog. The second was a 10 mile stint on the stationary bike. Although the bike ride took almost twice as long (37 minutes opposed to 18 minutes), the step count is similar. So I have no idea why Fitbit estimated the bike ride SO high at 350 (it's often been almost up to 400). It is certainly no where near the same intensity as jogging (I keep my stationary cycling pretty leisurely, reading while I ride).  So I always go in and adjust the calorie count down ... but down to what?

The bike itself estimates a calorie count between 230-250 for my 10 miles.  The bike does ask for my weight, it knows the actual distance and the difficulty level ... so it should be right, right? Well ... not according to my HRM!

My Polar takes into account all my stats (weight, age, sex ... as does the Fitbit). Of course it also uses heart rate to calculate an exercise estimate. Generally, HRM are considered accurate for "steady state cardio" ... but less accurate for other activities. You can see my Polar comes in quite a bit lower (157 calories) than the bike readout. During my ride,  I never  got my heart rate up "in the zone" ...  even at a pretty steady 16mph, it doesn't feel like I'm working that hard.  I'm really using the time for reading, just doing it on the exercise bike so I feel less guilty about spending so much time with my books (Riding and Reading). If I can do both at once, whatever the correct calorie count ... at least it is something!

So as I gather all my estimates ... I most often take the lowest one. That is usually the HRM. The machine readout is generally highest, with the Fitbit somewhere in the middle. For a straight walk/jog on the track, the Fitbit and HRM are usually almost identical. For DVD workouts (cardio or 30DS) the HRM is generally higher than Fitbit. 

When I'm entering an exercise manually into Fitbit, Fitbit also subtracts a little bit to take BMR into consideration (what I would have burned during that time anyway, as Fitbit takes that into it's total estimate for the day). I really TRY to be truthful with my exercise estimates. I know it does me no good to overestimate the numbers ... my body will burn what it burns no matter which estimate I write down.

Do you feel you are getting accurate calorie burn estimates? 
Which devices do you trust most?
How important is an accurate exercise calorie count to you?

It isn't just the calorie count that has me confused ... my "step" count for my bike workouts come in vastly different some days. Generally, my Fitbit and Omron pedometer are fairly close at the end of the day. As I'm averaging 22,000+ a day, variations of a few hundred don't seem bad. But I noticed on some cycling days, I was getting some big differences (2000+). 

Here's a snapshot of a before/after ...
Now I must say upfront here ... pedometers are NOT really meant to track cycling. I know this. For my own personal records though, I like to get step "credit" for the times I'm on the bike. I move my pedometers to my sock (NOT how they are intended to be worn) and get some "step" credit close to what I would have received if I'd spent the same amount of time on the treadmill or elliptical. But you can see (above) ... the two devices can count "steps/revolutions" VERY differently. It's not always the case though, here's another workout ...

... on this day, the counts stayed almost exactly the same!  
I'm not sure if I'm placing them differently or what. 
I guess I'll just have to continue to experiment.

 I found this interesting article.
Fitness Trackers and Calorie Counts

and check out my updated post
More Exercise Estimates

21 comments:

  1. I don't count the number of calories I burn. I am impressed, though, at your thoroughness in doing so. I just get on the stair master and go for five minute intervals. I don't know how many calories I burn, but it makes me sweat like a ho in church, so I figure that means I'm burning. When it starts getting easier, I speed up the stair master. I also use the weight machines at the highest weight I can for ten repetitions. If I can make it past ten reps, it's time to put the pin in the next higher weight. Oy, it never gets any easier!

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  2. I use the FitBit and love it. In your opinion is the Polar worth the $$ if I already have the FitBit?
    I am thinking about putting it on my Christmas list.

    Thanks for linking up!

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    1. I love the Fitbit most, it's just so easy! At first I wasn't too impressed with the HRM. Just a bit of a pain to put on and while not really uncomfortable, I'm always very aware I have it on. But it does provide some interesting feedback that the Fitbit doesn't. I think I like it more during the workouts (seeing my changing heart rate) then just to get a calorie count. I paid about $50, and I do think it was worth it for that. I do plan on doing a post/review at some point in the future!

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  3. I really hate that using all these different methods and you get all these different crazy numbers. I would *tend* to think that the HRM would be the most accurate of them all at least. Very interesting post!

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    1. I'm a bit of a numbers geek ... so I collect them all. *Ü* Even though I think the machine estimates run high, I still write them down and compare them workout to workout, to judge if I worked harder or not.

      I'm waiting for someone to invent an implant that can accurately give a calorie count for exercise and eating! No cheating! And even if there was such a device, I still wonder if a 3500 calorie deficit would equal a pound loss, or if there are still many other factors at play.

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  4. This is interesting... I've never heard of a Fitbit, but I do use a HRM when I workout. I like to think it's pretty close to accurate. Someone a long time ago told me you burn approximately 100 calories by running 1 mile and it's always stuck with me. Since that takes me about 10 minutes, I always think 10 minutes of activity = 100 calories. With my 20 minute Jillian Michaels DVDs, my HRM estimates 200-250 cals and during my 1 hour HIIT workouts it estimates 500-600 cals. I've seen 700+ a few times, but rarely! I thought I was going to DIE in spin class the other day and after 50 minutes it said 669.

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    1. In my sidebar, my most popular post is one that tells all about the Fitbit. I LOVE it. It's just so easy. I've heard that 100calories for a mile too, and it does seem fairly accurate. That is a good goal, 100 calories per 10 minutes. I try for that on my elliptical (I can get the machine reading to say that, but Fitbit comes in about 170, HRM about 140) ... stationary bike is quite a bit lower and my Jillian workouts I can't quite get up there.

      Regardless of what our devices say, our bodies are burning. I just want to eat enough to fuel it properly, but keep my intake low enough to lose.

      Thanks for commenting :)

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  5. Hi Jen! I think I'd believe those lower numbers. I tracked my calorie input (eating) v. calorie output at gym for 4 months straight. The cardio machines at my gym were big liars, according to the pounds I lost. After that, for several years, I still wanted to believe that I could eat like a guy if I exerted my fitness with the same effort of a fit guy. Well, that kept me in a bigger size than necessary. Now I look to gym for how the pounds of my body look and feel, but not as much for weight loss. Although, I do believe I keep off from 10 to 20 pounds just from keeping fit. :D

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    1. Guy DO seem to have it a bit easier, don't they? I write down all my machine numbers, mainly to compare one workout to another, but I am going with the lower estimates ... and I'm still wondering if I'm coming in too high, or if I just need 5000+ (not 3500) to lose. I was happy to have a slight shift today. I do exercise for fitness ... and just to get my tv watching and reading in without feeling guilty! I hope it helps with weight loss too though.

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  6. For a lot of the reasons you talked about I only use my Garmin. It does everything I need and I'm comparing apples to apples with my workouts.

    Thanks for linking up with Fitness Friday! Would you mind helping spread the word by using the Fitness Friday button in your post or on your sidebar? Thanks so much!

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    1. I do have the Friday Fitness button in my sidebar (it's down a bit, but it is there). I'll try to include the button on a post as I link up in the future. I'm planning on doing a post dedicated to link ups. They are such a fun way to connect with other bloggers. Thanks for hosting!

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  7. I rely on my HRM but you are right there are so many different estimates out there it is crazy!

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  8. Oh, and thank you for linking up with us!

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  9. The only way to get the true amount of calories burnt during exercises is to be hooked up and breathing into a metabolic machine as you exercise, so all of the above devices are an estimate anyway. If I can find the study, it was reported that one should take off at least 15% of the reported calories at the end of the workout. If I find it, I will email it to you.

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    1. I think I've read that article (or one similar). I know all these devices mean well, and they are probably better to have some sort of reference than nothing at all. But I really would love to know exactly what I was burning ... I don't know that I'd want to workout on one of those metabolic machines even if it was an option though :)

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  10. I love getting different estimates. I really want a heart rate monitors, but it's great how the fitbit syncs right up to MFP. Of course, I would have to remember to wear it in the first place! I haven't been a big fan of the fitbit because I never remember the darn thing! Or I wear it around the house and forget it when I change to my running clothes.

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    1. I'm obsessive about my Fitbit, I ALWAYS have it on and have for over three years. I got Fitbits for my two oldest boys (18 and 14) and I've been surprised at how well they have kept them on (the oldest has the Flex, the bracelet, but the 14 year old has the One). You do have to wear it *Ü*

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  11. I agree with Jill in that I only use my Garmin with its HR Monitor if I want to get a good estimate of calories burned.. but to be honest I use it more strictly to see where my HR is during a workout. I think gaining a better understanding of how different types of workouts effect your HR is really valuable. It is surprising how “non aerobic” activities like weightlifting can be aerobic if done efficiently.
    I have found the best gauge as to my diet/exercise effects on my body is the mirror and scale in the morning. If things are progressing in the right direction than I am doing things right… if not then analyze what needs to change.
    Good Post!

    Chris
    http://www.mavrocatstrength.com

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    1. Thanks for your comment. At first I wasn't too impressed with the HRM (mine is a Polar) but I've come to appreciate seeing the changes (or lack thereof) in my heart rate depending on what I'm doing. I think I like watching the numbers during the workout as much as getting a calorie count afterward.

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  12. You have got to be a type A :) haha I always go by my HRM which I think is the most accurate, machines are always off by a lot!

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  13. Calorie estimates are tough! When I run, I estimate that I burn about 80 calories per mile. If I get on the treadmill, it says I burn about 106. I know that is just plain wrong! I pulled the number 80 out of my ass, but I think it is a more accurate estimate. With other exercise, I gauge my intensity level and estimate what I think I burn per minute. I know these are just estimates... but they have been working for me so far! If I'm on a machine like the arc trainer, I actually only count 2/3 of what it says I burn because I know it over estimates so much even though I put my weight in!

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