V Core

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Has anyone done a V Core class?

I've noticed them advertised at the gym I go to (virgin active) and wondered if anyone could explain them?
Seem to be between 15-30 minutes so am guessing some short activity focusing on core?

Would it be best to do this sort of class before/after cardio? I sometimes find doing a class such as body pump okay AFTER attack/combat etc but awful if I do it before.

Thanks in advance! x