This is why we struggle with the virus while many other countries have it under control. No one is willing to make sacrifices for the greater good. We are a society of spoiled brats who get upset when the headphones we ordered on Amazon take three days instead of two.
When you breath hard during exercise/sports you produce a very high load of aerosols that can carry the virus. When you yell or talk with a raised voice during or right after breathing hard you also emit a very high load of aerosols. This is why there have been incidents where the virus spreads rapidly among team mates who do strength training in the same gym together. The risk of aerosols spreading outside is considerably lower than inside, but there still is a risk.
Mask wearing helps reduce the risk of transmission, but does not provide 100% protection. A lot depends on the quality of the mask. There is evidence that neck gaiters and masks made to be easy to exercise in do a very poor job of holding in aerosols.
And then there is the problem of compliance. Kids are kids. You may be able to get them to wear masks in competition, but there will always be instances where kids blow it off in practice.
With transmission rates still being very high in the US and Michigan, it is virtually guaranteed that there will be a very significant amount of transmission in high schools. This is very dangerous because HS age kids have parents who are mostly 40+ years old and are at higher risk for complications. And HS age kids have been shown to be able to transmit the virus as efficiently as adults.
HS sports are not so important that we need to risk additional transmission. The only responsible thing to do is cancel the season and wait until there is a vaccine or transmission rates are near elimination levels. Letting kids compete with masks is not a responsible compromise. It is just setting kids up for failure. Sports are not that important. Kids need to keep their parents safe and need to go to class more than they need to play sports for one year.