In the 1980's commercial gyms became prevalent and very popular, making men like David Lloyd very rich indeed. The difficulty they faced although were women- how do you get them into the gym? They didn't want to raise weights and were threatened by having to share the squat rack with the unbelievable Hulk. As they say, necessity is the mother of invention, and a Cardiovascular training ethos was born. It was marketed as 'a mild way of exercising'. (Lipowski 2010)