Catrine Tudor-Locke* , Hidde P van der Ploeg* , Heather R Bowles* , Michael Bittman* , Kimberly Fisher* , Dafna Merom* , Jonathan Gershuny* , Adrian Bauman* and Muriel Egerton*
International Journal of Behavioral Nutrition and Physical Activity 2007, 4:45doi:10.1186/1479-5868-4-45