Julien Bertrand is a sociologist, with a PhD in sociology at Lyon-2 University. In his thesis he studied the socialization of professional football players (Making Footballers: Sociological Analysis of Vocation-building, Dispositions and Know-how in Professional Sport Training, 2008). It was subsequently published in book form (La Dispute, 2012). His work has focused mainly on the training of sporting elites and socialization in childhood, particularly through sport and physical exercise. Much of his time has been devoted to analysing socialization and incorporation processes, and more broadly the conditions of social mobility, of production and reproduction of social groups and gender.