Is treadmill running speed accurate?

JimFiore wrote:

dukerdog: I am surprised that you found errors both fast and slow, especially within a fairly narrow pace range. I have never seen that.

But you probably haven't seen too many 10-year-old treadmills tested? Admittedly, I checked each speed only once, but I would have had to make a pretty big mistake to change the fact that one speed was too fast and one was too slow.

Keep in mind that they are probably not actually measuring the speed that they report. More likely, the machine is using some nonlinear speed vs. voltage to the motor relationship that was determined at the factory. That relationship could have changed quite a bit after 10 years.

I know a girl who has never run in her life nor is she in any kind of shape who one day decided to run on a treadmill. She ran 18 min. for 5k. So i don't care what anybody says....I wouldn't take a time off a treadmill and count it as a legitimate time.

MarathonMind wrote:

but were the inaccurate ones within 10 seconds as Jim Fiore said?

Also, readers should scan this other thread for possible answers:

http://www.letsrun.com/forum/flat_read.php?thread=625093&page=0

i think that is the overall best treadmill thread on letsrun.

"the way you run on a treadmill is nothing like that which you run outside. You dont have to propel yourself forward on a treadmill, this changes your entire style. If you simply bounce higher and let the ground float under you you are saving energy. You cannot account times on a treadmill for real running."

I bounce with my two-year old, I run on a treadmill. Did you read this before posting or are you just drunk?

ex-runner wrote:

"the way you run on a treadmill is nothing like that which you run outside. You dont have to propel yourself forward on a treadmill, this changes your entire style. If you simply bounce higher and let the ground float under you you are saving energy. You cannot account times on a treadmill for real running."

I bounce with my two-year old, I run on a treadmill. Did you read this before posting or are you just drunk?

---------------------------------------------------------------

I am gonna go with he was drunk.

"Fat drunk and stupid is no way to go through life, son." I think Dean W. was talking to you.

dukerdog wrote:

But you probably haven't seen too many 10-year-old treadmills tested?

This is true. My first TM is still less than 10 years old and I never had a chance to look at the guts of 10+ year old TMs.

Keep in mind that they are probably not actually measuring the speed that they report. More likely, the machine is using some nonlinear speed vs. voltage to the motor relationship that was determined at the factory. That relationship could have changed quite a bit after 10 years.

This is also (possibly) true. Ultimately, it would make a lot more sense to have a sensor on the drive belt and use that to generate a feedback signal rather than use a static setting, partly for the reasons you state, plus better performance with differing loads. My current Bodyguard TM has an optical sensor for this purpose. I never took a close look at my old Pacemaster so I can't report on that. I have noticed that many TMs are set up to change by .1 MPH increments. The pace (mins/mile) display is probably taken from a simple look-up table in the microcontroller. The display on my Bodyguard always truncates the fraction (e.g., a speed of 8.6 MPH is 6:58.6 pace but the unit displays 6:58 instead of rounding up to 6:59). I know it's only one second worse-case, but it shows up when you do the calibration.

luv2run: Thanks for the abstract. It is good to see that they corroborated the non-linear increase in wind resistance as pace increased. There's a nice chart in DRF showing this effect. For this reason I've always done my tempo work (6-ish) at 1.5% and VO2max intervals (5:30-ish) at 2%. All I can say is that when I've made the transition to an outdor track in the Spring, things seem to be right in line effort-wise.

I have read many times about making a slight adjustment in incline or speed to compensate for a treadmill's lack of wind. However, I have to tell you whenever I have done an interval workout or tempo workout on our treadmills at work (with no adjustment), it always seems harder than when I do them on a track. Not sure why that is. I'm sure it's just in my head, but that's how it feels.

True, and Jim Fiore figured prominently in that discussion as well. I'd like him to let us know what other areas of expertise he can share with us. :)

MarathonMind wrote:

True, and Jim Fiore figured prominently in that discussion as well. I'd like him to let us know what other areas of expertise he can share with us. :)

I'll share one other topic where he figured prominently:

Thanks. Quite the thread. Filled with all sorts of analysis, high drama, and repartee.

Ugh. I will make the leap of faith that you're not yanking my crank and are just curious, so I'll answer. I don't have many "areas of expertise". I'm an electrical engineer, so I simply have a decent grounding in physical science and mathematics (professor, actually, focused on audio electronics and digital signal processing). My hobbies include music (been playing drums since grade school), so I have some formal knowledge of that. I guess you might say that I'm an expert on electronic drums as I've done a lot of work in this area over the years (a rather small area to be an expert in, that's for sure, but you can check out how the electronic drummers live by going to a site like

www.edrumming.com

) I also like history (esp. science and political history), cosmology, and a bunch of other things to dabble with instead of watching game shows and "reality TV" but those make me an "educated layman" at best.

I have very little knowledge of pop culture. I only found out who Paris Hilton is about a year ago. Although I am aware that shows called American Idol and Survivor exist (or existed, are they still on?), I have no idea who has ever been on them or what they do. I have never been inside of a Wal-Mart.

There. More than you ever needed (or wanted)to know.

Not yanking anything at all Jim. Just curious as I am an architect and enjoy these fun little diversions as well.

And since you like electronic drums, here's a fun program I've enjoyed with my daughter:

http://pbskids.org/cyberchase/games/patterns/patterns.html

(hint: you should skip to the "next" array on that page as it has more combinations)

doesnt flagpole play the drums? ever thought of forming a band with him?

Don't be dumbasses. Any treadmill that is digital will be accurate to a hundredth of a mile. IT IS DIGITAL!

SHEESH!

You can cheat on a threadmill by leaning into the bars. This in a sense takes a few pounds of the legs. On the roads you have nothing to support you.

JimFiore wrote:

Also, using a fan helps to remove the microenvironment of warm air that builds up around you. If you do those two things I'd say that the mechanics/effort are as close as any two road circuits you might compare.

Yes, the fan part is often overlooked. Another way to put it is, If you assume that incline can accurately compensate for the lack of wind resistance then your HR would be higher running on the treadmill. While providing resistance the wind also helps cool you down. Without it, your heart must pump more blood to your skin for cooling and has less of it "left over" to transport oxygen to your muscles - hence it must circulate faster.

The treadmill I have now is reasonably new and it is off by 15%.

It is digital and has a very nice display.

I like the treadmill.

However it is not accurate, and being digital has nothing at all to do with accuracy.

I'll wager that less than 10% of treadmills on the market today are accurate within a 1 percent range, and probably not within 3 percent. At a 6:40 pace that is 4 and 12 seconds respectively.

And I'll bet most treadmills are not accurate within 5%, which is +/- 20 seconds at 6:40 pace.

Digital? You could slap a digital display onto just about anything but that doesn't make it accurate. I have a DIGITAL odometer/computer on my mountain bike and it's calibrated to within 1% using a local certified race course as the base. I could take that unit off and slip it onto my road bike and the accuracy would be crap (road bike has much larger wheels). For that matter, I could tape the unit to my neighbor's dog and then the accuracy would be completely out the window.

I suspect (but have no proof) that the accuracy of inexpensive TMs may be quite a bit off (perhaps 5% as JR suggests). I think higher end home units (that's probably JR's 10% or so) ARE accurate to within 3%. In terms of sheer numbers, there's got to be a lot more $400 Sears, Weslo, etc. TM's out there than $3k Pacemasters, Trues, Precors, Bodyguards, etc. I think the letsrun demographic probably skews ownership to the higher end.

JimFiore wrote:

For that matter, I could tape the unit to my neighbor's dog...

Oh, no you don't!!