“Low intensity exercise （Low intensity exercise is defined as working at a heart rate of about 60% to 65% of your maximum heart rate ）only burns calories while you are actually exercising. That means the moment you stop exercising, your caloric expenditure goes back down to nearly baseline levels. Within minutes, you're not burning many more calories than if you hadn't done anything at all.

High intensity interval training , on the other hand, continues to boost your metabolism long after you're done (often up to 24 hours after, depending on the length and intensity of the training session). This means you're continuing to burn many more calories all day long!“

我用过从80年到到现在的很多跳操录像，很明显的区别：早期强调40分钟以上比较low impact的动作，现在的加了很多high impact的。对于很多刚开始运动的人来说，high impact就已经是无氧运动了。

从我自己感觉，现在我的routine比用以前的减肥效果好。