American cardiologist Arthur M. Master (1895-1973) standardized the 'two-step' exercise test (currently known as Master two-step) for cardiac function.
In 1942 American surgeon Austin T. Moore (1899-1963) performed the first metal hip arthroplasty.
The Douglas bag was also used in the army. In the case of pilots, oxygen consumption was shown to increase at cold temperatures. On the photo one can see how a pilot is tested at a temperature of -20°C.
Belgian physician Lucien Brouha (1899-1968) introduced in 1942 the 'Harvard Step-Test' in the world-famous 'Harvard Fatigue Laboratory', which was in many ways comparable to the original master test. He was widely used to measure the condition in sports centers, and a form of it (the grip test) was used for military purposes. A variation of this, the Schneider test, was also popular when evaluating military personnel. These tests used the number of impulses during recovery and provided an index of physical fitness, a technique that would be transmitted in the indices of fitness and aerobic power for a number of years. Brouha and C.W. Health also used the methodology to evaluate the cardiovascular response in different professions and emphasized the influence of environmental factors such as room temperature.