Cécile Grenier helped establish the modern concept of female physical education. In 1927, she worked at the Montreal Catholic School Commission teaching gymnastics to primary and secondary students.  In 1937, she served as the Assistant Director of Physical Education, where she led the organization of physical education in schools for girls. In 1939 Cecile founded the l’Institut d’education physique in Montreal which taught instructors to teach gymnastics and physical education in schools and camps throughout Quebec.

During the 1940’s, Cecile perfected her studies in new approaches in female physical education.  Very active in her teaching profession, she was responsible for the training of physical education teachers from 1937 to 1971.  In 1948 Cecile was appointed by the Department of Education to build a new fitness program for classes from the first to the eighth grade. Throughout her career, she championed children's and women's physical education by providing both theoretical training courses and practical sport and recreation opportunities.