After finishing medical school, he served as an interne (1878), working as an assistant to neurologist Jean-Martin Charcot (1825–1893) at the Salpêtrière and Bicêtre Hospitals in Paris.

In 1883 he received his medical doctorate with a graduate thesis on Basedow’s disease, being promoted to médecin des hôpitaux several years later (1888).

[1] Marie was the first general secretary of the Société Française de Neurologie, and with Édouard Brissaud (1852–1909), he was co-founder of the journal Revue neurologique.

From 1928, Marie left the medical academy to become a political journalist, first at physical-culturist magazine La Culture Physique, where Edmond Desbonnet served as his intellectual patron.

[3] He became increasingly involved in the SFIO in the 1930s, gaining a reputation as the Party's foremost intellectual on matters of sports, leisure, and physical culture.