Physical fitness and specific motor performance in pubertal boys: Ghent youth soccer project - Philippaerts, R.; Janssens, M.; Stoops, F.; van Renterghem, B.; Craen, M.; Matthys, D.; Bourgois, J.; Vrijens, J. (Book of abstracts of the 6th annual congress of the European College of Sport Science, 15th congress of the German Society of Sport Science. Cologne, 24-28 July 2001, 2001)