I've been doing spin classes for a little over a year (met my goal of 100+ classes for 2013).
I have worked with a sports physiologist to have both my resting metatolism and my VO2 Maximum tested (I've had this done three times over the last few years.
With the results of these specific tests, he was able to give me a grid showing exactly how many calories I burn in a hour at various heart rates..
During a typical spin class I maintain an average heart rate of abound 140. At this rate I burn roughly 850 calories. My base metabolic rate is about 2350 a day or about 100 per hour. My NET calorie burn for a one hour class is, therefore around 750.
The bikes themslves always read much lower than this when showing calories burned (anywhere fro 350 to 500). The reason for this is that the bike only uses the Watts you generate to make a guess about your calorie burn. A heavier person for instance (I'm about 180), will burn many more calories when spinning in a standing position than a light one because they are moving their own weight as well as pushing the pedals. Likewise, doinng lots of jumps will burn more calories than just sitting although the watts will be the same.
| current weight: 180.0