I think I should warn (people) not to forget to warm up properly before swimming.
That's right. I also sometimes get cramp in my legs in the water, so please pay attention.
It first I thought ツッて came from 吊る and I read it as "dangle my legs in the water", but that makes no sense from context. So I checked the dictionary and found "to cramp". But the dictionary doesn't say that this is a transitive verb and it doesn't seem to me like it should be. So how can I understand 足をつる. How should I use this verb normally?