Quickerblade; You are so correct, just about anything keeping the heart rate steady at a higher lever for a certain amount of time (40 minutes may be too extreme for most) is the whole point. Most people reach a point of boredom very soon doing the same kind of cardio over & over again. That can go for weight training also. Most people think that cardio always involves some sort of running (track, treadmill, etc) or other exercises involving leg work. True that rope jumping, Spinning, hill/grade running are very affectice to reach a higher goal. The Schwinn Air-Dyne also add's a push-pull action (arms, shoulders & back) along with heavy leg pumping, upping the benefits of fat burning. Those new designed rowing machines can give anyone a outstanding cardio workout. Even punching a heavy bag demands and can build great endurance. Anyone might try doing somethin different every time they want to do cardio, if nothing else but for the sake of variety in training. Good Luck.
