The sentence 'Do some swimming' is correct and can be used in written English.
For example, you could write, "In order to stay fit and healthy, you should do some swimming each week."
"I was really busy because I was still swimming to keep fit and doing some swimming teaching," she said.
"He's also doing some swimming and, while we are playing catch-up with him after his hold-up, we're hoping to have him ready to run in one of the Derby trials".
"He went to the beach, did some swimming, saw his family and helped Jelena ahead of her graduation for an economics diploma on Sunday 12 June.
And this year we may well have to do some powerful swimming against strong economic currents to get to the finish line".
For now, I have to embrace the currents, hit a few rocks, maybe build a boat and do some real swimming.
Do some practice swims at your group level.
I try to do some running and swimming every day.
If your heart is racing, do some exercise, like swimming or walking around.
Walk, take the stairs, rather than escalators or elevators, play a sport, swim, do some gentle stretching, yoga or t'ai chi.
When Leigh Fermor came to the Mani he did some impressive wild swimming.
