Healed Hammy
Just a sillly question (although Sister Kevin in 4th grade used to tell us that no question was silly...damn her)
Recently my runs seem to feel easier even though I have been at this for just about 6 months. What made me notice was on Wed I ran on the treadmill for 7 miles at a 9:15 pace and that seemed much harder than todays 7 miles on the road at 8:45 pace. I know there are several factors, one being the temperature (basements are always warmer than outside), and calibration. My treadmill is about 10 years old and I've never calibrated since purchase (don't even know if you can).
Anyway, just a passing question as to the accuracy/chaning accuracy of the GPS function relative to speed and distance, and could Garmin or Obama (the govt) change the algorithims that drive the data that we all feed on?
Chairman
With a clear view of the sky, they Garmin watches are normally quite accurate. Typical measurement error is within 1% on a nice, straight course. Turns and major elevation change will reduce accuracy.
And yes, the government could make the GPS signal unusable or reduce its accuracy if it chose to do so. When GPS was first introduced, the signal was intentionally degraded for civilian users, a feature called Selective Availability. President Clinton turned off Selective Availability in 2000, likely because the military developed other ways to selectively block the signal when necessary.
Coalition for a Free and Independent New Jersey
delicate flower
Treadmill pace always feels harder to me. 8:40 pace on the treadmill takes a little work. 8:40 pace on the road is pretty effortless. Assuming my legs are fresh in both cases.
Regardless of what treadmill I am using (gym, fitness center at work, YMCA, a hotel), I use the readings from my footpod and watch, so I know I am getting a consistent reading each time no matter how uncalibrated the treadmill is.
<3
TM pace always seems too easy to me but I run in horrible weather outside.
I think the GPS is fairly accurate but it depends on the cloud cover (as scrape said) and other issues surrounding your route. I've had the same route telling me it's 7 miles and another time telling me it's 6.95.
Damaris
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No more marathons
GPS is more likely to be short rather than long, especially if your run has lots of turns (as in a mountain trail). But even so, it is not going to be off much.
Interesting side note: I have a Garmin 205 that I used for about 3 years. When it when belly up I got a 210, but sent the 205 back for rehab. Once I had both watches, just for chuckles, I used both on a roughly four mile run. The older 205 read 4.15 miles, and the newer 210 read 4.05 miles. Go figure.
Boston 2014 - a 33 year journey
Lordy, I hope there are tapes.
He's a leaker!
Treadmills seem like more work for the same pace, until I remember to run like I am outside, as opposed to trying keep up with the speed of the stupid belt.
Your cadence can get away from you so to speak running on the belt and thus, the run may seem harder.
The next time you're on it play with slowing your cadence but keep the same speed. There is a difference in perceived effort...at least there is for me.
All other things (rest, hydration, fuel) being equal, running outside always feels easier to me than running on a TM. I haven't yet noticed a discrepancy between the readings given by my 210 and iPhone apps like RunKeeper or MapMyRun.
Walk-Jogger
TM pace always seems too easy to me but I run in horrible weather outside. I think the GPS is fairly accurate but it depends on the cloud cover (as scrape said) and other issues surrounding your route. I've had the same route telling me it's 7 miles and another time telling me it's 6.95.
I'm no math wizard but my calculator says that's a variation of only 264 feet in 7 miles, or about 7/10ths of a percent. That's close enough for a training run. My measured straight out and back 10k course with a clear view of the sky is usually repeatable within 1 or 2 1/100th's of a mile. I run it as 6.21 miles when I'm running it for time, just to be sure.
Retired & Loving It
My only problem is when I"m doing a route I've done 300 times and the same Garmin starts saying I'm 1/10th of a mile behind. It is minor, but it screws up the pace (makes me slower).
sugnim
This NY Times article claims that GPS watches are not completely accurate: GPS Watch Can Be an Unreliable Running Partner
Consumer grade GPS watches are good enough for what we need, but are not 100%. And that's why they will rarely measure a race course for the exact distance. I actually did some GPS art earlier today on a frozen lake, and I ran in the same exact path to trace out some words several times. Yet, the finished product showed my path moved by several feet each run.
Take Charge. Train Harder. Suck Less. No Excuses.
Consumer grade GPS watches are good enough for what we need, but are not 100%. And that's why they will rarely measure a race course for the exact distance. I actually did some GPS art earlier today on a frozen lake, and I ran in the same exact path to trace out some words several times.
Now that is a really cool idea.
Are we there, yet?
You might find this article, In GPS We Trust, an illuminating comparison of the relative accuracy of GPS and course certification.
2024 Races:
03/09 - Livingston Oval Ultra 6-Hour, 22.88 miles
05/11 - D3 50K 05/25 - What the Duck 12-Hour
06/17 - 6 Days in the Dome 12-Hour.
GPS is accurate enough for everyday training but not accurate enough for a race. People seem to think that a GPS is infallible because it's electronic. Go figure.
Short term goal: 17:59 5K
Mid term goal: 2:54:59 marathon
Long term goal: To say I've been a runner half my life. (I started running at age 45).
Chief Unicorn Officer
Yeah, don't get me wrong, I love my GPS, but I know it's not 100% accurate. It does bug me when people are all like "the course was advertised as X but my watch said Y, so the race director LIED!!!" and then they flip out. A lot of my local courses have twists and turns in them which I know affects it, so if I run a PR on a course that measures 3.07 miles on my GPS, or 3.25 miles on my GPS, I count it. They're not perfect.
Mile 5:49 - 5K 19:58 - 10K 43:06 - HM 1:36:54