The Tabata protocol (developed by Dr Tabata, Japanese sports medicine national center) is one of the better forms of interval training. Requires 20 seconds of full out effort, than 10 seconds complete rest. No tension on the resting muscle area during those 10 seconds rest. A spin type bike(among other ways) was used in the development of this training method.
The aerobic and anaerobic are both worked at or near the highest V02 max capacity's and at the same time. Results: encourage fat burning, even at a resting state between workouts. Does not affect muscle mass, while long durations of cardio may limit or even cause muscle mass lose. Usually 2 or 3 workouts a week are only required for most.
T-tones has an exceptional level (even at 15 seconds rest) of fitness to get 8 cycles done. Top level athletes will usually do from 6 to 8 cycles. Doing more that 8 cycles would be counterproductive in most cases. The spin type bike is an excellent choice. Rowing machine are also used with outstanding results. A friend of mine works in a high rise building in Century City (LA) and he does the Tabata method running up stairs, during his break time. Seems to clear his head for the rest of the day. Good Luck.