My foster son was beside himself at the thought of sports day when he was younger. He said that he always comes in last and gets "the sympathy clap".
That was true and humiliating for him. He was going through a particularly difficult time anyway.
I spoke to my social worker who said it was not fair to force him to do it and to kick him when he is down.
I therefore told school he wouldn't be taking part in any of the races etc. Therefore I could keep him home or he could be a helper on the day.
They agreed he could be a helper. He wore his PE kit and sat with the other kids, but when they went off to race, he'd be helping set up etc.
Nobody really noticed he wasn't involved in the races and he was happy and felt important. It worked well.
However, at one point I saw a teacher almost trying to force him to take part, and I could see my boy starting to get upset, so I went to nip that conversation in the bud!
It was probably easier for me as I had social workers backing my decisions at school.
I would add that he's now doing GCSE PE and is SO sporty!!!