First off, happy Halloween to all! Enjoy the candy, wine, or whatever you will partake in this evening/weekend! Remember it is important to let loose a little (in moderation) in order to maintain a healthy lifestyle.
As a trainer I pride myself on the fact that I'm continuously checking out and try different gyms in my area and see what types of fitness classes that they offer. From what I've noticed most of them seem to be putting their own spin on High Intensity Interval Training or HIIT for short. HIIT has become increasingly popular over the past 10-20 years.
HIIT training originated with Sprint interval training which involves short periods of anaerobic exercise followed by recovery