Translation:I do gymnastics.
What is the ます form of.the main verb itself here? Why isn't that the form used, rather than the one with the auxillary?
The ます form is やります.
ています form is the continuous form. It means I am doing gymnastics, or I do gymnastics constantly as a habit.
This can be both. やっています can be "I am doing it right now", or "I practice it regularly".
I thought regularly is yarimasu and it should be im practicing it.
Anyhow my knowledge got rusty, have to read up on it again.
Because Gymnastics was already specific. if it wasn't specific you can use 'the' word.
E.g (not specific one) . " I will go to the Hospital" ... this hospital can be any hospital not specific one like "Maryland Hosptial / Neo Hospital" ..
if it's the specific one just remove the 'The'.. e.g (specific) : "Tommy went to Tokyo Dome last year". not The Tokyo Dome
My english isn't that good , but hopefully this helping
*Sorry for my bad english
Just one remark when to use SURU and when to use YARU: https://japanese.stackexchange.com/questions/15383/differences-in-usage-between-%E3%81%99%E3%82%8B-and-%E3%82%84%E3%82%8B
Could this also be "I am doing a warp-up"? I put that but it got marked wrong