Garmin Forerunner 235 - Running a track indoors

I've had pretty good distance accuracy running on a treadmill. A couple times it was off by bit, but an acceptable amount for me. If your indoors, I doubt you'll get a useable GPS signal, so you probably won't see the circles anyways. I think your only option is to use Run Indoors then later you can rename the 'Run Treadmill' activity to 'Run Indoor Track'.

Max

That sounds like a good idea! Maybe I'll opt for just renaming future exercises.

Indoor running mode would be more accurate for track running, I'd say

It's my understanding that the distance tracking on a treadmill run is less accurate. What is the best option and how would I set it up?

Both the ‘outdoor’ GPS-tracked running mode, and ‘indoor’ or ‘treadmill’ running mode, have limitations in your use case. My understanding is that:

GPS-tracked running
Distance = ∑‖[FONT=Times New Roman]p[SUB]i[/SUB]-p[SUB](i-1)[/SUB][/FONT]‖ where [FONT=Times New Roman]p[SUB]i[/SUB][/FONT] is the location of the object as determined by the [FONT=Times New Roman]i[/FONT][SUP]th[/SUP] GPS reading

GPS – in theory – determines distance travelled more objectively, by observing the moving object from an extrinsic perspective. However, the technology has an inherent margin of error (of single-digit number of meters in ideal operating conditions) in pinpointing the location of the object, which can be significant relative to ‘slow’ speeds (such as typical human running speed), especially when combined with non-linear movement around ‘tight’ corners or curvature. Sampling frequency also has an impact on the accuracy in measuring total distance travelled.

Indoor running
Distance = ∑[FONT=Times New Roman](m[SUB]i[/SUB]n[SUB]i[/SUB])[/FONT] where [FONT=Times New Roman]m[SUB]i[/SUB][/FONT] is the stride length and [FONT=Times New Roman](m[SUB]i[/SUB]n[SUB]i[/SUB])[/FONT] the step count for the [FONT=Times New Roman]i[/FONT][SUP]th[/SUP] split
(Typically, stride length is assumed to be the same for every split.)

Indoor running mode typically counts the number of steps continuously (as opposed to sampling at intervals), and then multiply the step count by a nominally representative stride length to determine the distance travelled. Wrist-worn devices are likely to have a larger margin of error than footpods for counting steps, but from what I've seen on my FR235 it's fairly accurate in that respect. However, stride length is personal and influenced by many factors, including but not limited to the grade or slope of the ground (which is fortunately very consistent for a track), the shoes and other gear worn while running (which you can keep consistent), the level of fatigue, etc. If your stride length is consistent for track running, with little variance from the mean stride length information you provided to the watch, then the distance will be quite accurate. If the user does not provide that information, but leave the watch to guess at it by default values and/or other user profile data, then the accuracy may suffer.

Given that the track is of a known, fixed distance, I think it would be easy for you to track several runs in typical conditions, and determine your average stride length (i.e. distance divided by step count) with a high level of confidence that it will be representative of future runs in similar conditions. I'd say using indoor running mode would therefore be the better option for your use case.