With Dad Bod, you will be doing four 25 minute metabolic circuit training workouts a week. (flexmastergeneral.com)
Intense exercise such as HIIT and metabolic circuits sharply reduce ATP and promote lactic acid build - up and increased tissue acidity. (womenshealthandfitness.com.au)
Between metabolic circuits, HIIT and resistance training, this philosophy has been slowly forgotten, but it's definitely not obsolete. (chriscoulsonfitness.com)