Running Pace Way off

How do you know you ran at 5.15/km?

Anyway, instant pace does tend to wander a bit, so I normally use either lap pace or a smoothed pace (there re CIQ data fields that do this) and that is far better than instant pace

No I don't think you should. I do most of my running under tree cover. The only time I see pace fluctuations is when I change pace, certainly not when I come out into the open and back in to the trees. There's a regular 'blip' there which I'd argue probably shouldn't be there. Would you post a link to the actual activity?

Yes a link to the actual activity would help to better comment. Were you really doing the pace you say and was it even effort. I ask myself if I "knew" I was doing a certain pace without a Garmin why would I wear one.

One of the local running clubs runs a relay once a year where no watches are allow. They tell you the length of the course at the start and you have to predict the finish time for everyone in your team. No-one every gets it right. I know I am horrendous at running to a pace. I thought that running flat out would be the easiest way to do this, but depending on the elevation and how tired you are this can easily vary by 15secs/km.

Link to the activity: https://connect.garmin.com/modern/activity/2324630658

I maybe was not spot on 5:15 all the time but I know what pace I do on that lap on the given heartrate without efforts and the fluctuations in pace just don 't reflect the constant pace I was running. (it certainly never dropped to above 6:00, while the activity shows a lot of +6:00 pace.

What I also noticed:

- my workout was almost 0,5km shorter than the one my father records if he also does the same amount of laps I did.
- In the southern part of the lap I go back and forth on the same path. On the map in 2 of the 3 laps when going back I'm 30m to the right of the path.

Hard to say, but if you plot pace vs step length you do see a very nice correlation, so perhaps it's not so crazy afterall... But yeah, instant pace IS flakey :

Maybe not so consistent after all then. Our perceptions about how we run are often far from what we actually do. Your route has sharp turns and reversals where your pace will almost drop to zero too. Can't say for certain, but I wonder if those abrupt pace changes are more a reflection of that than anything else. Do you have auto pause on? If you have turn it off.

Auto pause is off.
Isn't the step length calculated from Pace and cadence? Than it makes sense they are on par.

Some sharp turns indeed, but with 1 second recording on I would expect it to pick up the pace after the turn quicker.
I also think 0,5km difference over a 7km run is too much, no?

True, that would make sense... was actually looking for something like cadence but couldn't see it so took this instead. But indeed, if calculated from pace it's not saying much ;)

As an aside where has cadence gone - can't see the graph of it although it is present in the lap and overall summary states.