Greg Glassman, the creator of the fitness regimen CrossFit, didn't become one of the most powerful people in the fitness business by being coy. On Sunday's 60 Minutes, the brash executive behind the largest chain of gyms in history calls for the sale of CrossFit's partner brand, Reebok, from its owner, Adidas, to "someone young, fresh." Glassman gives a candid interview and opens CrossFit's offices to Sharyn Alfonsi for a profile to be broadcast on 60 Minutes Sunday, May 10 at 8 p.m. ET/PT.

CrossFit creator Greg Glassman and Sharyn Alfonsi CBS News

In just 15 years, Glassman has built a worldwide fitness empire that uniquely combines elements of weightlifting, calisthenics, and gymnastics. In addition to the millions who practice it in thousands of CrossFit gyms, 270,000 recently competed in the CrossFit Open. The best go on to the Regionals and then the CrossFit Games where the winners are crowned "Fittest [Man or Woman] on Earth." Last year, the final days of the competition attracted 45,000 spectators and was featured on ESPN. Athletic brand Reebok sponsors the Games and has shared in the success of the CrossFit brand.

Many believe a recent turnaround in Reebok's fortunes has a lot to do with its association with CrossFit. Reebok has been owned for almost 10 years by the German athletic giant Adidas, but there have been persistent rumors Reebok would be sold. Adidas' CEO recently quashed such rumors of a sale just as Reebok reported strong sales for the first quarter of 2015.

"I'd like to see Reebok sold," says Glassman. "[To] someone young, fresh, excited, and willing to enter into the modern era of things," he tells Alfonsi with a laugh. When a wide-eyed Alfonsi points out that he has just made a very bold statement, he doubles down. "Isn't it?"

Glassman has been generating such stares for years. Earlier in his career as a personal trainer at gyms in California, his workout routines, which would form the basis of CrossFit, were perceived as loud and disruptive. It got him tossed out of other people's gyms several times he says, because he wouldn't change his style. "Oh, I don't mind being told what to do. I just won't do it. Say anything you want," he says.

CrossFit has been criticized by some for being dangerous and causing injuries. The few studies that have focused on the safety of CrossFit found it to be about as safe as weightlifting or gymnastics and less likely to cause injury than running. When Alfonsi asks Glassman his response to someone who says, "...This all sounds interesting, but I've heard things and I don't want to get hurt?" He replies, "Stay in your chair where you're sure to get hurt, and you'll become one of the 300,000 people that will die next year from sitting in their chair doing nothing."