He graduated from the Ecole Nationale Supérieure des Arts Décoratifs Paris, in 1968, after completing the very first course in “ esthétique industrielle ” (industrial design), a discipline that evolved as a branch of architecture. After completing his studies, he and a group of friends cofounded the Design Centre Premier, the first group of associate designers in France. His partners include Xavier Mérigot (graphic designer), Jean Foin (urban architect), Jacques Verger (screenplay writer) and Dominique Prevot (industrial designer). During this time he collaborated with important brands in the fashion industry such as Pierre Cardin, Ted Lapidus, and Torrente. He designed logos for Ted Lapidus and Torrente and perfume packaging for Yves Saint Laurent and Pierre Cardin. In the early 70’s, the long recovery following the fracture of his right foot and ankle due to a skiing accident, along with his passion for skiing, pushed Marc to find a solution to reduce the risk of accidents by immobilizing the ankle. After quite a few attempts, the first completely recyclable thermoplastic rubber ski boot was manufactured.
Between 1973 and 1974 Sadler’s partnership with Italian sports companies in the North–East grew stronger. He mainly worked for Lotto, being responsible for designing all products and logos. Lotto at the time was manufacturing shoes in Italyand was considered one of the most innovative brands, both aesthetically and technically, along with Nike, Puma, and Adidas.