Antagonist training allows you to recover more quickly between sets due to the arrangement of the nervous system. When you activate a muscle group with max effort the nervous system inhibits the opposing muscle group for greater movement efficiency. This phenomenon decreases the time necessary for recovery and it helps restore strength. You’ll be able to perform your opposing muscles in less time than if you performed each body part separately, and you’ll be stronger.
Due to the intensity of the workout, HIIT can elevate your metabolism for hours after exercise. This results in additional calories being burned even after you have finished exercising.
So, the combination of the two is a phenomenal way to build muscle and burn fat.