Ever hear the terms “metabolic conditioning” or “metcon?” More than likely, the answer is yes. Metcon training is a hot term in the industry right now, with coaches and trainers from various disciplines putting clients through the grueling paces of YouTube-worthy sweat sessions. But as with any workout protocol, success lies as much in the programming as it does the effort. Metabolic conditioning should be difficult but “tough workout” isn’t the lone classifier.

Here are 5 must-know facts about metcons that can help you start building a physique replete with muscle that burns fat around the clock.