Between 1934 and the outbreak of World War II, Brouha travelled on scholarships on several occasions to conduct research at universities in the United States.

Having been imprisoned during World War I, he left Belgium for Paris due to increasing tension with Nazi Germany in early 1940.

He moved to the private sector in Canada in 1944, where he helped shape the field of ergonomics, but retained connections to various universities.

As a high school student during World War I, Brouha Jr couriered dispatches and was imprisoned by the Germans when they discovered these activities in 1917.

[2] Brouha's physical fitness recovered after his release, and he took up the sports of field hockey and sprinting, as well as rowing, which became his main interest.

Alongside Victor Denis and Marcel Roman as rowers and coxswain Georges Anthony, they went to the 1924 Paris Olympics where they were eliminated in the round one repechage.

[11] Lucien Brouha and his researchers found a 40-percent error rate with the AZ test, which they modified by switching from female to male mice.

[14][15] In October 1932, Brouha was appointed as lecturer at the Higher Institute of Physical Education (HIPE) in the Faculty of Medicine at the University of Liège.

Brouha was particularly impressed by the work undertaken by August Krogh in zoophysiology at the University of Copenhagen, and by Edgar Atzler [de]'s work at the Kaiser Wilhelm Society for Occupational Physiology in Dortmund (now the Max Planck Society; the building where Atzler was based is now the Max Planck Institute of Molecular Physiology).

Major connections were with Peter Karpovich [de] at Springfield College and with Walter Bradford Cannon at HFL.

Brouha's early research at HFL expanded on experiments on dogs that he had previously carried out with Corneille Heymans from Ghent University.

[17] The tension in Europe preceding World War II weighed heavily on Brouha's mind and in February 1940, he and his wife left Belgium to join the French National Research Council in Paris; shortly after, in May 1940, his laboratory in Liège was destroyed through bombardment during the German invasion of Belgium.

Guy La Chambre assigned him to the French Air Force, where he worked in the Laboratory of the Medico-Physiological Services with physiologist André Mayer [fr].

He had, however, been asked by Cannon and Lawrence Joseph Henderson to move to Harvard on several occasions following his 1930s research visits, and in August 1940 he answered their calls and arrived in Boston.

During 1943, the HST was promoted to schools and colleges, with the idea being that fitness would not improve if exercise was either too strenuous or too easy, hence it was better to grade students prior to physical training.

[23] From late 1945, Brouha was in parallel professor at the Université Laval, where he was jointly leading the Institute of Hygiene and Human Biology with the biologist Louis-Paul Dugal.

[27] For private industry, Brouha studied the physiological problems that workers experience and through this work helped shape the field of occupational ergonomics.

[28] Brouha's younger brother Paul (1910–1943) was a resistance fighter who was caught by the Germans in early 1943 and executed at the Citadel of Liège on 31 May 1943.

[32] Brouha died on 6 October 1968 "after a long and painful illness"[32] in Liège, Belgium; he was survived by his wife and their four children.