Are my sentences correct? Can I use them instead of "Do you exercise?"
1."Do you do any exercise?" 2."Do you do exercise?" 3."Do you do any exercises?" 4."Do you do exercises?" I am asking about BrE.
Are my sentences correct? Can I use them instead of "Do you exercise?"
1."Do you do any exercise?" 2."Do you do exercise?" 3."Do you do any exercises?" 4."Do you do exercises?" I am asking about BrE.
All your examples are correct. "Exercise" is both a noun and a verb.
As a noun, the singular "exercise" can be a collective term for any number of individual exercise routines, but you can also refer to those individual routines, for example, situps, burpees, crunches, etc with the plural "exercises". So you could say:
According to the Cambridge Dictionary, the noun exercise can be countable or uncountable. For most uncountable/countable nouns, the uncountable form refers to something in general, for example cheese or sugar, whereas the countable form refers to a particular type. Cheddar, Edam and Roquefort are cheeses: and sucrose, fructose and glucose are sugars.
The same applies to exercise: It is used in the uncountable sense to refer to exercise in general... physical exertion of any kind is uncountable exercise. It is used in the countable sense to refer to a specific kind of exercise: squats, arm curls, etc.
Looking at your sentences, 1 and 2 refer to exercise in general, 3 and 4 refer to specific kinds of exercise. 1 and 2 are normal questions, whereas 3 and 4 sound a bit strange because the question doesn't seem to be about specific kinds of exercise. This question would make more sense for the countable form, because it is asking about specific kinds of exercise.
What exercises do you do?
In the same way, "do you like cheeses?" sounds wrong, but "what cheeses do you like?" sounds fine.