Longer is better.....or so they think

I have been teaching indoor spin cycling classes for about 10 years now. It's an enjoyable activity for me as I am able to get a super-intense workout completed in a relatively short period of time. For years, the classes at my club ranged from 45min. to 60 min.....we even had the occasional 2 to 3 hour marathon classes usually offered on the day after Thanksgiving, Christmas etc. (you know, the big guilt days). I recently started a 30min. "High Intensity Interval Spin" class....I mean we ALL know the effectiveness of anaerobic-style training on fat loss, fitness, even aerobic system benefits right? Uhh, apparently not all of us do... I mean I get one of the best workouts of my life during this 30 min. class, usually dropping more calories than I do in a HARD 45 min. spin class...crawling off my bike as I leave the room. When I look around at the rest of the class, however, I just don't see the effort that I would hope to see in such a short spin class (ahh, the dreaded comfort zone...). To top it off, my 60 min. class is completely full (55+ people) most days....my 30 min. interval class maybe gets a dozen members. People just don't see the value in coming to a class that's "only 30 minutes". It's to bad, we have come a long way in this field when it comes to conditioning concepts.....it just hasn't trickled down to Joe or Jane-Gym goer!