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Fitbit Product Experts Alumni are retired members of the Fitbit Product Expert Program. Learn more
@Heybales - Hi. I got involved in a similar thread a few months ago, and I am not sure I want to go there again, it gets a little too time consuming.
But to answer your more direct question as to "But you said it - speed of motion. How do you get speed of motion?", that would be the time elapsed between each time your One's sensor senses the impact of your heel on the ground. The shorter that time frame, the quicker the pace. Makes sense? You can a person with a very long stride length walking very slow, with a shorter person with a much shorter stride length, both walking the same distance and arriving at the finish line holding hands - there is no doubt in my mind that the shorter person will not only show more steps but also more VAMs because of the increase intensity of her/his walk in order to keep up with the person with the longer stride length.
I thiknk what people often confuse is the speed of an overall walk - say a 4.3 MPH one hour walk; as compared to the speed and intensity of movement, in every 60 second segment, during a walk. A one hour walk at 4.3 MPH, all subject to one's BMR profile of course, does not guarantee 60 VAMs. But if every single minute of that one-hour walk was at or above the VAM threshold, yes, that person will indeed earn 60 VAMs. But we all know that that there will be peaks and throughs - and thus, it's only those 60 second segments that met the VAM threshold that will count towards VAM, because only those minutes had sufficient intensity and speed of movement to warrant them. Makes sense?
There is no argument that fitbit is not aware of the additional effort for inclines; and even when it does, in instances where the elevation is continuous and greater than 10 feet, it doesn't even grant additional caloric burn credits! Go figure! Nothing is perfect in this world, but when it comes to pedometers, I think the One stands tall at the top of the class IMHO.
Regarding you last question, stide length comes into play to measure distance travelled, not VAMs. And yes, both our One's showed the same distance, give or take. Distance is never exact, as you know - it's far from GPS accuracy and the tracker assumes that one's stride length will be exactly the same throughout a whole one-hour walk, which can't be. But yes, both our recorded distances were reasonably the same. By the way, this is just one walk - we've been doing these walks together since August 2013, so we've had ample time to compare stats and sometimes get into some pretty edgy conversations - "Well how come you..."
The factors that come into play for calculating VAMs are the number steps, time, pace (speed of movement) and so a lesser degree force of impact. This last factor (force of impact) is news to me and the result of tests done by other contributors to these forums, @Colinm39 and @slysam who were able to demonstrate that indeed the force of impact will work towards VAMs.
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@Heybales- I promised myself I wouldn't get back into those lengthy discussions, no matter how interesting they become, and here I am again!
I will just make a couple more points and then I will butt out.
When you say "To get the VAM, starts at 5 x that resting calorie burn value or 5 METS, but your pace must be 4.7 mph or better." The say people earn VAMs with their trackers depends largely on one's BMR. My wife will ear VAMs a lot easier than I can during our one hour, same distance, walk, because she has to work much harder than I do in order to keep up with me; and at 67 years of age, I can assure you that her speed is a far cry from 4.7 MPH. I also earn VAMs 3.7 - 3.8 MPH range.
I don't disagree with your definition of pace - but pace, in the context of discussiing a pedometer, does not refer to the overall speed of travel over an entire walk, but the speed of movement, the quickness with which you take each step, and the number of steps within each 60 second segment of your walk.
On that note, I will gladly let others continue the discussion, I have to go and walk and earn more VAMs.
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@Heybales - You're doing a wonderful job draggin me back into it, aren't you!
First, let me just say that I don't profess to be Mr. Knows-it-all here, but just my humble opinion, from one fitbit user to another, and nothing more than just that. With that in mind, let me try to address some of your comments.
"So if it depends on your BMR, that means it's the total calorie burn."
Well yes and no. One's BMR enters in the algorithm, along with the number of steps and the intensity of those steps. But VAMs are aggregated in 60 seconds segments as opposed to the overall duration of an activity. You can jog at an average speed of 4.5 MPH for an hour; but during that hour, there will be minutes where you slacked off, sped up ... The algorithm will look at every single minute, assess each one individuall, and report them to VAMs. If you use the timer function for a run and then look at your activity log and click on the small clock icon, you can readily see your peaks and throughs, where your earned VAMs. But if one was to run at a constant speed for a whole 60 minutes, at a speed that for him/her (given their BMR profile) exceeds their VAM threshold, then yes, he/she would bget a full 60 VAMs.
"Because 4mph 1% grade is 5.4 METS for everyone, but when you throw the BMR in there, now it becomes a factor of total calorie burn, so not relative."
I am not sure I follow you here. By definition, BMR has to be included in measuring the intensity of any physical effort.
"But I've seen ones commenting on that too. If it was BMR and total calorie burn, a lighter person would never hit VAMS, a heavier person would easily hit them. If pace was decent."
No that's not true. I lighter person would indeed earn VAMs; but the lighter you get, the harder you have to work to ear them. I can tell you that I have to work a hell of a lot harder at earning those VAMs now that I've lost 43 pounds or so. Just thinkg about it - just take to 20 pounds dumbbells, one in each hand, and go for your 5 mile walk. That's what I was doing day-in and day-out. So once I decided to change my lazy habits and get moving, I was shedding those pounds and earning VAMs big time! I stil earn them, and I still earn as many, not because they're as easy to earn than when I was over weight, but rather because I am fitter, lighter and have a lot more energy to do much more than I used to.
"Unless they are actually going by adjusted METS now, compared to older method. Newer method is getting your BMR down to calories / kg / hr. METS value x that figure is calories burned.
Old method was just 1.2 cal / kg / hr assumed average resting metabolic rate in calorie burn."
Frankly, you're lost me here. No comment.
"You are right on the 4.7 mph, that was for manually entered step based exercise, not live stats, which was lower."
HA HA! Got ya!
"With comparison with wife, I guess they must include steps as part of formula. They say private method of calculating it, probably so they can change it at any time. I know the biking requires a higher calorie burn per min that 5 METS when I log it to get VAMS."
Of course they include steps. The number of steps you take in a 60 second segment, subject to your BMR profile, will dictate whether or not the steps taken in that one minute qualifies or not as a Very Active Minute. The intensity (i.e. the force of impact) will also come into play, albeit to a lesser extent I think. Part of your profile when you set up your account at fitbit.com includes your stride lengths, one for walking and one for running. These are not meant to be exaggerated measurements but your normal strides. When you accelerate your pace and the tracker's sensor realize the quickness of your steps and the bounce in your step, it will automatically assume that you're now running, not walking; and it will use your running stride length to calculate the distance. And when that happens, it will also use this information in its aggregation of VAMs - but the key factor here is not the stride length per se, but the speed of movement and the force of impact, and the bounce in your stance.
"And yes, I meant pace as in step by step based. Here is default stride length, here is time of each step, here is impact of step, how does that compare to expected for mass and stride length, running or walking, bigger or shorter stride, ect."
Let's not kid ourselves, it's all based on METs tables, thus all based on averages. If we fall within the norm, than the metrics we get will be more or less on target. If we fall outside the norm, than the results will be somewhat skewed; but over time, for the purpose of monitoring one's performance improvements, those metrics will work just fine, the reasoning being that the error factor, whatever it is, should be relatively constant.
OVER AND OUT - THIS TIME I MEAN IT, NO MATTER HOW GOOD THE BAIT IS!
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