[toni-a]

Well, as it is for me ISO 8000 is the absolute highest I'd go, and even then I bear in mind that if I'm shooting that high, the lighting is probably too lousy to get any decent result anyway.
All along the track, I've seen the resident marathon photogs set up ambushes with "proper" lighting because they have to get clear shots of every runner they can (so that those can buy the photos later). I can't imagine doing the same - and moving all across the city loaded with that stuff - though.

In any case, mostly I'm shooting daytime sports anyway; the nocturnal marathon was an exception because it has been moved to its original time frame after years of being "just another" marathon.

Daytime sports that's rather easy for the gear, my 7Dmkii is just awesome for this, even with slow lenses like 15-85 and 70-300f4-5.6 I had very good results.

[Rover]

Well, yeah, for daytime I would stick to the usual set of 16-35 and 100-400 most of the time, maybe also 24-85 or the 10-17 fisheye when I feel adventurous. Anyway, shooting this nocturnal marathon was an interesting challenge, although I've been also suffering from health issues after that (not necessarily due to that, as I would not make this assumption just yet). The full gallery is here:
https://topdialog.ru/2022/06/13/skorost-tmy-peterburgskij-marafon-belye-nochi-snova-stal-nochnym/
(and Google Translate can do an at least not outright bad job translating this into English if you're interested in the text too).

[jaapkaru]

I tended to use the 24L mostly indoors, in cafés, pubs and restaurants, at night, with awful lighting, and it always performed exceptionally well under those conditions, including AF, even on my 5D and 5D II.

vidmate mobdro