explanation please

[123gogo]

Well, I've tried to get my head around this a few times....but I still can't figure it out! I've been running the same route for the last while...(cause it's shady and a beautiful, soft run on my knees) and I've been running with NRC - either to track the distance or time. For the last few weeks, NRC told me that this route was a 5 km run. Average speed 6-7 min/km. Fine. A week or so ago I tried to slow my run down to about 7-8 min/km. I did the same route and NRC told me I had run less than 3 km. Hmm. Today I did my normal speed, same route and NRC tells e I've run 4.17 km and 8 mins/km.

I don't care about the times. And the cadence is similar but WHY is there such a discrepancy in the distances? I thought maybe the slower times could affect the info going into the NRC (free, basic) program but then no, a kilometer is a kilometer just like a kilogram is a kilogram. These things don't change.

Maybe the NRC program is messed up but for the life of me, I can't understand it. Can someone please explain it to me? Thanks in advance

[IannodaTruffe Mentor]

Maybe your GPS is playing up.

[John_W Graduate Ambassador]

Welcome to the inaccuracies of GPS

I assume that you do not have a running watch but are using your phone instead?

[nowster Graduate]

Did you put your phone in a different place today?

GPS is a very fragile signal. Lots of things affect it.

[123gogo Graduate]

no watch, just the phone, always in the same place.....

from the replies, I'm assuming that there is no logical explanation, it's just the blips of modern technology. Which relieves me- I was doubting myself, thinking there must be some logic that I couldn't understand- and it was driving me nuts! Thanks, all!!

[Cmoi Graduate in reply to 123gogo]

If I'm tracking my runs I often use both my Garmin and Strava, and they never give the same results, whether for distance or elevation gain. Strava is usually more generous, but today it measured way less.

[Hedgehogs123 Graduate in reply to Cmoi]

I run only with my phone and headphones but have Strava on in Kms and NRC in miles, I find they are always slightly different, but when I do Parkrun Strave is usually the closest to the actual Parkrun time.

[Yesletsgo Ambassador Graduate]

Kilometres are longer on NRC for me. The local Parkrun measures as 4.88 km, and if I run a km with Garmin NRC usually notifies me about 0.2- 0.3 km later. I was thinking of Tweeting Coach Bennett and asking him what's going on but I don't really use Twitter so maybe someone else can 😂

[Hedgehogs123 Graduate in reply to Yesletsgo]

I've contacted Coach Bennett several times on Twitter and he directed me to the Nike customer support team. I have to say they were very helpful. I'm sure it was just @nikeservice If it's different I'll amend my answer with the correct Twitter address.

[Yesletsgo Ambassador Graduate in reply to Hedgehogs123]

Thank you, now all I need to do is to get to grips with Twitter!

[Apecouch]

Is your calculation on a stepchecker? I know when I used a pedometer it asks for stride length etc...I'm probably way off the mark but?!? Hey-ho...

[AT17W]

I have the same issue when using a distance measured guided run as opposed to a timed run on NRC. On Monday I did a 7 miles guided run - I was on fire as I completed it in 1hr and 3 mins according to NRC. If only!! I had only actually covered 5.63 miles according to my garmin, and knowing the route I was doing, plus my average pace, there was no doubt which measure was correct unfortunately! 😉