the length is important—and the requirement of classic pop songs, which can vary from two minutes to four minutes. J. Randy Taraborrelli, in his book Madonna: An Intimate Biography, described Faure's song "24 Hours" as a slow track that fails to build up momentum. Joe Brown from The Washington Post described Davidson's "Turn it Up" as consisting of a slow background synth, that transforms into a rapidly progressing beat, with Davidson's singing reminiscent of the Beastie Boys. Promotion Tour Madonna performed "Who's That Girl", "Causing a Commotion," and "The Look of Love" on her 1987 Who's That Girl World Tour. It was her second concert tour, promoting True Blue and the soundtrack. Madonna trained herself physically with aerobics, jogging and weight-lifting, to cope with the choreography and the dance routines. For the costumes, she collaborated with designer Marlene Stewart, expanding on the idea of bringing her music video characters to life on stage. The stage was huge, with four video screens, multimedia projectors and a flight of stairs in the middle. Leonard became the music director and encouraged Madonna to go with the idea of rearranging her older songs and presenting them in a new format. Madonna named the tour 'Who's That Girl', after looking up at a gigantic image of herself projected on a screen on the stage during rehearsals. The show consisted of seven costume changes, with song-and-dance routines with an encore consisting of the title song "Who's That Girl" and "Holiday". The tour also addressed social causes like AIDS, during "Papa Don't Preach". Who's That Girl tour was critically appreciated and was a commercial success, grossing a total of US $25 million, with Madonna playing in front of 1.5 million people over the course of the tour. According to Pollstar, it was the second top female concert tour of 1987, behind Tina Turner's Break Every Rule Tour. Singles "Who's That Girl" was released as the lead single from the soundtrack, on June 30, 1987. A latin pop influenced song, it became Madonna's sixth single to top the Billboard Hot 100 chart, making her the first artist to accumulate six number-one singles in the 1980s, and the first female performer to get that many number-ones as a solo act. It also reached the top the charts in United Kingdom, Canada, Netherlands, Ireland and Belgium. In the music video Madonna did not portray her film character Nikki Finn, instead