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bunnyemerald

How do pedometer apps distinguish length of stride?

10 years ago

How does a pedometer, specifically an iPhone app such as Pedometer++, account for the different length of one's steps throughout the day? How does it distinguish between long outdoor strides and small steps in the kitchen or while working in the garden?

Yesterday a friend and I took a walk together outside on a nice level surface. My app uses GPS and hers is a simple pedometer app. Mine reported 3.5 miles and hers 3.0. I'm confident my distance is more accurate, as I've tested other apps and driven the same simple route in my car.

For the first time ever I tried to measure my outdoor stride. I walked back and forth across 20 ft. of my living room and got 9 steps pretty consistently = 26.6". A couple of my apps give 26.4" for a woman 5'4" and I'm going with that. But I was amazed that it was within .2".

But what about all those little steps while making the bed, putting groceries away, etc. Those aren't long strides.

Comments (30)

  • 10 years ago

    Jim, I think you're right. But she assumed it was accurately tracking her distance, à la GPS-based apps. Personally, I'd rather know distance than steps. Steps don't matter to me. Should they?

  • 10 years ago

    There are fitness programs that emphasize counting steps.

    Bunny thanked User
  • 10 years ago

    If 2 people are the same weight and build, the person who uses more steps to complete a mile uses more calories then someone with a longer stride.

    Bunny thanked maddielee
  • 10 years ago

    maddielee, that makes sense. So distance alone is not necessary the sole criteria, although it happens to be for me because that's what exercise means to me. I did notice that my friend, although we're the same height and possibly my legs are shorter, I was taking longer steps than she, even though we were walking at the same speed. She probably weighs 25-30 pounds more than I do, so how does that factor into it.

    Also, since she took more steps than I did (not a huge amount but more), why would that have translated to less distance. Her app keeps a running total of all her steps for the day so I can't ask her what they were for our specific walk together.

  • 10 years ago

    >She probably weighs 25-30 pounds more than I do, so how does that factor into it.

    All other factors being equal, a heavier person is going to burn slightly more calories than a lighter one doing the same action.

    Bunny thanked writersblock (9b/10a)
  • 10 years ago

    Steps based programs are based on number of steps, has nothing to do with calorie burn. Step based programs are goal based. 500 steps today, 600 next week, etc.

    Bunny thanked User
  • 10 years ago

    Okay, this is making sense. My friend really is interested in distance but now understands that her app is step-based. I think she's going to switch to a GPS app.

  • 10 years ago
    last modified: 10 years ago

    All of these data are approximations and can vary by 10% when compared to laboratory validation. The best data are the raw step counts. Previous researchers have found that calculating for stride length, distance, calories expended, etc., are less accurate than the raw step counts. I work in this area and have many professional colleagues in this research. 2000 steps approximately is 1 mile but there is variability.

    Measuring and estimating free-living energy expenditure is not as easy it may look. All of the fitness trackers do a decent job, but no one is perfect.

    Bunny thanked gsciencechick
  • 10 years ago

    gsciencechick, what do think of GPS tracking? I consistently walk a couple of routes near by house and the results are quite close.

  • 10 years ago

    I use a Fitbit, and I'm always amazed at how off it can be. I run often on the treadmill, so I know exactly how far am running. The fit bit is always at least 3/4 to 1 mile less in measured distance.

    Bunny thanked jojoco
  • 10 years ago

    Yes, I was just going to post that GPS walking apps are just not reliable. I can't tell you how many Camino blogs I've followed where the person is happily recounting that today I walked 27 km, 32 km, etc.. only to stop counting in the middle after realizing that their GPS showed them as having added 5 km while they were seated at the table for lunch.

    Bunny thanked writersblock (9b/10a)
  • 10 years ago

    My street is a horseshoe and one lap on my GPS app is consistently 0.25 miles. Today I drove two laps and it was 0.5 miles. I realize there's going to be som difference since I walked on the sidewalk and drove on the street, but it seems accurate enough for my purposes.

  • 10 years ago

    That's just what I'm saying, Linelle. Next time, try walking two laps and then standing around for ten minutes in the middle of a third lap, or leave it on and go out shopping and stop for lunch and see what happens. They're rarely obviously off when you do a simple test like you did.

    Bunny thanked writersblock (9b/10a)
  • 10 years ago

    Honestly, I am less familiar with the research validation of the GPS apps vs. the devices. My guess is the distance is probably reasonable, but looking at something like kilocalories I would doubt because there so much individual variability. But probably OK for a ballpark figure or to make comparisons within an individual.

    Bunny thanked gsciencechick
  • 10 years ago

    gsciencechick, all I care about are distance and time, no interest in steps or calories. I know that my cruising speed is 3.4 mph. I know what it feels like without the app even telling me. I exercise to stay healthy and in shape. Weight is not a problem.

    wb, I'll try stopping for a bit as I do a street lap. I never leave it on all day. Typically I start it as I head out my front door and stop it when I return. The only stopping along my walk is to tie my shoe.

  • 10 years ago

    I walked a 10 mile road race route wearing my fitbit, and at the end of the race it only showed a little over 8 miles, and I had also walked around the house, from the parking lot to the start of the race, etc.

    You can measure your walking and running strides and enter that into the app to make it more accurate, but I haven't bothered to do it yet.

    Bunny thanked terezosa / terriks
  • 10 years ago
    last modified: 10 years ago

    i like to drive my routes to get a pretty good idea of distance, but can't do that on trails... if you know your speed that you're walking and know that you keep a pretty consistent pace, that's a somewhat decent gauge too...

    overall, i like underestimates rather than overestimates!! is it really that important to get an exact mileage??? as long as you walk for your hour or hour and a half or what ever distance you prefer and keep your pace, why does it matter about exacts?? (when walking trails i up my time when i want to up my distance...)

    Bunny thanked busybee3
  • 10 years ago

    terriks, just yesterday I measured my walking stride and entered it into my app, so it will be interesting to see if it makes any difference.

    busybee, you're right. Since I always walk at the same rate on the same 2-3 trails, I pretty much already know the distance. However, sometimes I'll take a new turn into a different neighborhood and lose myself in thought and be curious about how far I walked. Also, my app has a nice report feature where I can choose a span of days and get a total distance. A couple of years ago for Lent my goal was to walk 100 miles. I didn't meet my goal, it was around 50. I just like numbers and stats and this is the one I've chosen to track.

  • 10 years ago

    I use a fitbit and it can be off by quite a bit...I notice it esp on stairs. But I like that it uses gps when I walk, esp when I walk in the woods where google maps can't measure mileage for me. At least I get some idea.

    Bunny thanked Annie Deighnaugh
  • 10 years ago

    Annie, exactly. I became curious about walks that can't be driven, and that led to being slightly obsessed with actual distances. I know it's not exact, but in the ballpark, give or take .2 of a mile.

    My friend keeps her iPhone (with pedometer app) in her pocket most of the day. So she is logging everything at home and at work at a school where there's a lot of walking to and fro across the campus. The only time my phone is in my pocket is when I'm deliberately going on a walk. Otherwise it's in my purse and I'm not sure there's as much motion detection accuracy in there. At home it's on the counter or table.

    I'm curious about the real distance diagonally from one corner of Target to the other other.

  • 10 years ago
    last modified: 10 years ago

    lol- yes, i can understand how it can become almost like a game.... my hub and kids were always into running and the stopwatch for time was a constant with my hub... as he's gotten older (and slower) and as our kids are no longer competing as often, the stopwatch is more of a memory! lol

    also, he's amazingly accurate with measuring with his stride- a full stride =~ 1 yd... you can measure your full stride (numerous times to increase accuracy! :) and then stride target diagonally to get a pretty good idea! ;)

    Bunny thanked busybee3
  • 10 years ago

    I am a runner so having an accurate calculator for distance and pace is very important to me. I have found anything associated with a phone GPS to be completely inaccurate. Sometimes grossly inaccurate. There are tons of articles on the Internet explaining why. I bought a Garmin watch and have never looked back. Completely accurate in distance and pace in the last few races I have run.

    Bunny thanked Caroline Hamilton
  • 10 years ago
    last modified: 10 years ago

    my hub used to occasionally have some trouble with his garmin watch for distances- sometimes it used to pause for some reason...

    i haven't used my phone gps for walking, but mine, i think, is very accurate for distance- it lines up with my car odometer quite accurately... i know it tells distance and predicted time for distance through google maps for a walking path as well as a driving route- maybe those are all sidewalk routes tho- i haven't looked into it...

    Bunny thanked busybee3
  • 10 years ago
    last modified: 10 years ago

    know it tells distance and predicted time for distance through google maps for a walking path as well as a driving route

    That's a google maps function, not necessarily anything to do with the watch. Both Google and Siri will give you a walking route if you ask, but they have some decidedly odd ideas of good places to walk. I know that from sad experience.

    Bunny thanked writersblock (9b/10a)
  • 10 years ago

    Yeah, Siri doesn't always know the best and most logical route from A to B, but I'm consistently impressed by how well she readjusts when I go off course. A couple of months ago she was already giving detour routes when traffic was backed up due to a downed tree a couple of miles ahead of us.

  • 10 years ago
    last modified: 10 years ago

    I took a test walk with three apps. Can't really report back because one without GPS runs all day and had some steps from earlier errands. I forgot to note the number, so I'll have to repeat my test tomorrow.

    But...as I was walking I started questioning an assumption I've had. I have two apps with GPS, one I use all the time, another I have used sporadically in the past but I've brought it back.

    I have always assumed that it was the GPS that was tracking distance, and that number of steps was just a stat I didn't care about. Now I'm wondering if even my GPS apps are step-based and all the GPS is doing is mapping my route. It's fairly accurate in terms of location; you can see where I went one way for 10 ft., changed my mind, then went in another direction. :) The only real value to me of the maps is it's a record of where I walked and that's kinda cool.

    But what if it is all happening at the step level and GPS is just an enhancement?

    However, today two apps that I started at the same time and turned off at the same time (both GPS) reported the same distance within 0.032 of a mile, yet the step count was off by 420, with the slightly longer distance reporting the fewer steps. Interestingly, that app has no discernible way to configure step length beyond telling them my gender and height.

  • 10 years ago
    last modified: 10 years ago

    Yeah, Siri doesn't always know the best and most logical route from A to B,

    That, too, but I meant that she thinks that the swale of a freeway is a swell place for a stroll. (So does Mr. Google, BTW)

    I spent three days from hell under the domination of Siri when walking from Paris last fall. Never, never, never again. One day they tried google and that was very slightly better, only evidently his database for walks is not very current because we kept getting confronted with waist high nettle thickets where you could see there might once have been a path.

    Me, I prefer a map and compass.

    Bunny thanked writersblock (9b/10a)
  • 10 years ago
    last modified: 10 years ago

    Just had an interesting read on an Apple forum about the accuracy of the Health step counter. A couple of people claim that they get different counts depending on which pants they're wearing! Others depending on which pocket it's in. The theory is that with a tighter jeans pocket the phone is held snugly and gives a more accurate count, but bouncing around in a roomy shorts pocket will record extra (false) steps.

    I feel like I might be chasing my tail.

  • 10 years ago
    last modified: 10 years ago

    LOL Linelle. Very timely. DH and I spent about 5 hours walking around Central Park last Sunday. I don't carry my iPhone around with me most of the time so don't usually pay attention to the Health step/mile counter. It occurred to me today that I had my iPhone with me all the time on Sunday so I checked the stats. Said I walked 9.57 miles. DH checked his and it said 7.36 miles. I did walk a bit more than he did that day but I don't think two miles more. At most a 1/2 mile. My phone was in my jacket pocket and his in his pants pocket (I think). I wouldn't think those would be very different. Interesting. Maybe my jacket "bounced" and added distance?

    ETA - Just occurred to me that I took about 40 pictures with my phone and DH took 2. Does the movement of the phone for pictures get counted as person movement? Hmm.

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