I did a run interval session today with automatic lap intervals on my garmin watch. Therefore when these intervals went through to strava, they displayed as exactly 2 minutes each. Even if I use the ‘use laps’ option under analyse, it seems to assume interval length and get some of them wrong? e.g. some are 1:57, 2:02 etc, and the total number of intervals is incorrect.
Activity is here: https://intervals.icu/activities/3781906393
Intervals.icu uses the logged data from the activity and the indexes of the intervals in to calculate the time etc… Your watch is only logging a data point every 1 to 5 seconds so there will be quite a bit of variation on the time for each lap depending on the intervals between the points at the beginning and end.
Lap 3 (first work lap) from Strava has start_index=167, end_index=218, duration 120s, distance 557.76m. The actual activity data looks like this (time is seconds):
index time distance
167 533 1584.6
168 535 1592.5
...
218 652 2136.3
219 656 2149.7
So you can see the varying time gaps between logged points. Intervals.icu uses an exclusive end index for intervals (Strava is inclusive) so the Intervals.icu end index is 219:
Index 219-167 time: 656 - 533 = 123 seconds
Index 218-167 time: 652 - 533 = 119 seconds
Index 219-167 distance: 2149.7 - 1584.6 = 565.1m
Index 218-167 distance: 2136.3 - 1584.6 = 551.7m
So whichever way it is done the activity data does not match up to the reported lap data (2 minutes and 557.76m). Intervals.icu has to use the activity data to support editing of intervals and so on so I can’t just “cheat” and override the activity data with the reported lap data for the laps.
I don’t know if it is possible to get your watch to log every second? That would help.
With regards to how the laps are turned into intervals, Intervals.icu considered some of the later “recovery” laps as work due to their high HR. You can just delete these (easiest on the “Interval data” page) and then you get a clean set of 8 x 2m. I did this for your activity.
Awesome explanation, thank you. I can probably turn on more frequent polling, I’ll check it out.
Hey David,
I do have the same problem, but then not the same problem.
Nearly at any activity the use laps function does not work.
Here are just two examples. I hope you can help me.
https://intervals.icu/activities/4313143924
https://intervals.icu/activities/5013978292
I am using an elmnt bolt.
I looked at the first one and the lap data from Strava is iffy. Even Strava’s own lap display is off. If you have the original file you could try upload it to Intervals.icu and see how that works out.
Good idea. I will try that and see if it helps. Don’t know why, but it’s a problem with nearly every activity that all laps are off by the same amount. Every lap is starting early like the first lap is shortened. If direct import doesn’t work, I’ll get back to you.
Had the same issue today so I uploaded the file directly as a .fit file. And now everything works fine. Thanks for the tip.
So there must be some error on Strava… Is it maybe because of the privat zone I have on Strava? Because the files I record on my trainer don’t have the issue…
Is there an option to universally ‘use laps’ on all my workouts? Interval detection is nice, but typically I’m following a workout and the lap function is more accurate to the intervals I’m trying to complete.
Not yet but that is on the todo list.