Put Yourself First Pt. 2

This drives the blood back and forth between your upper and lower body, allowing you to burn about twice as many calories! The extra calorie burn results from something called peripheral heart action, or PHA. PHA is a good program, and it's one of the reasons we can get such great results. As if burning more calories weren't enough, following this kind of routine also reduces the formation of lactic acid, which is the cause of muscle fatigue.