Ryan's involvement with the workout routine has been documented extensively by Politico.
The program has been around for five years but it has seen a new surge in popularity since Ryan was selected as Mitt Romney's vice presidential candidate, according to Horton. From an interview he did with the New York Times this week:
“It certainly helps,” said Tony Horton, 54, a physical trainer from Santa Monica, Calif., who created the workout. Like a seasoned politician, Mr. Horton reached for a stump-worthy lesson. “The summertime is slow, so all this attention, it’s going to help us a lot.”
In an interview with FishbowlDC, Horton has said that he's also "aware that there are copies of the program in the White House.”