such systems work with a considerable delay, 20min or more. it does not measure blood sugar real time due to technical reasons.
i am type1, have used all such systems, currently using Dexcom G6 and still measure my sugar with a traditional device once in a while.
especially in more extreme situations where blood sugar rises (food) or falls (sports) very fast the CGM is considerably off (20-40%) for some time and shows delay of 20+ min.
so therefore I dont see any use for a “real time monitiring” in sports
Here is a thread with a similar discussion:
https://www.trainerroad.com/forum/t/supersapiens-continuous-blood-glucose-monitoring/43759/43