Wiktionary
high intensity training
n. (context sports English) A weight training system developed for bodybuilders.
Wikipedia
High intensity training
High Intensity Training (HIT) is a form of strength training popularized in the 1970s by Arthur Jones, the founder of Nautilus. The training focuses on performing quality weight training repetitions to the point of momentary muscular failure. The training takes into account the number of repetitions, the amount of weight, and the amount of time the muscle is exposed to tension in order to maximize the amount of muscle fiber recruitment.