In 1920 in Paris, the course 'Physiology appliquée à l'éducation physique' was the starting point for a chair 'Hygiène et organisation technique du travail humain', occupied by Professor Physiology Jean-Paul Langlois (1862-1923).
In his specially equipped laboratory, this pupil of Charles Richet (1850-1935) initiated a study into sports training and the return of muscle activity.
Danish Professor of Physiology August Krogh (1874-1949) was awarded the Nobel Prize in Medicine for his research into the increased oxygen consumption during muscular work. Given the oxygen pressure with resting muscles is rather low, the higher use had to be explained by an increase of the diffusion surface. Krogh concluded that new capillaries were opened during muscular labor, which had previously been closed and that the surface from which the oxygen could diffuse became larger. Together with his compatriot and colleague Professor Jens Lindhard (1870-1947) Krogh had taken over an idea from his German collegue A. Bornstein years before and developed the nitric oxide method to determine the general blood flow, which would become very important for further developments in that area. During muscular work an important increase occurs, which was attributed to varying heart filling during the diastole. The supply of venous blood must therefore be variable within wide limits and can hardly fill the ventricles during rest. This decision was reinforced by Krogh in his analysis of the underlying mechanism, which also led to the conclusion that the portal system in the central veins acts as a general pressure regulator and therefore affects cardiac output. All these discoveries were extensively researched in the following years and published by Krogh in his book 'The Anatomy and Physiology of the Capillaries' from 1922. Under the auspices of the 'League of Nations' Krogh carried out other researches on heavy muscular work and in 1934 a series of important problems were treated, such as heat regulation, respiratory metabolism, influence of diet on work capacity, blood sugar, lactic acid, training and fatigue and kidney function.
British scientist John Scott Haldane (1860-1936) designed a gas analysis device to determine the Metabolic Rate.
The device was described in 1920 on page 59 of the 'Laboratory Manual of the Technic or Basal Metabolic Rate Determinations' by Walter Meredith Boothby (1880-1953) and Irene Sandiford.
At the Universität Giessen in Germany, the institute for the Scientific Research on Physical Exercise was inaugurated under the stewardship of Otto Huntemüller (1878-1931), a Professor of Hygiene. In 1924 Huntemüller founded the German Federation of Physicians for the Support of Physical Exercise.
On 15 May 1920 the Deutschen Hochschule für Leibesübungen (DHFL) was founded in Berlin. August Bier (1861-1949), director of the Chirurgischen Universitätsklinik Berlin, became the first rector. First the Health Sciences department was in the hands of Arthur Mallwitz (1880-1968), then Max Rubner (1854-1932). A total of four laboratories were available.
The anthropometric laboratory was led by Wolfgang Kohlrausch (1888-1980), the physiological by Edgar Atzler (1887-1938), in close collaboration with the Kaiser-Wilhelm-Institut für Arbeitsphysiologie. The psychological laboratory was initially in the hands of Werner Schulte, but from 1925 Hanns Sippel took over the command, and finally the radiological laboratory. The enormous contribution that the DHFL made to the development of sports medicine research is unmistakable. The vast experience gained in sports medicine was brought together by Bier in 1938 in his work 'Sportschäden am Bewegungsapparat'.
The use of treadmills extended to the fitness world.
A photo on page 37 of 'The Laboratory manual of the technic or basal metabolic rate determinations' by Walter Meridith Boothby (1880-1953) and Irene Sandiford.
An stress test in Edingburgh for testing the physical readiness of the military.
British physiologist Joseph Barcroft (1872-1947) experimented on his own in a by him designed glass chamber.
Thus he spent six consecutive days at ever-decreasing oxygen concentrations. The room was equipped with a bed, a bicycle ergometer and all possible devices to measure the metabolism.
A photo of the physiotherapy room in the Goldmühlenbades of Burtscheid, a district of the German city of Aachen.
The photo above appeared in 'The Human Engine of The Scientific Foundations of Labor and Industry' by the French physiologist Jules Amar (1879-1935). Using a Chauveau valve, the exhaled volume of the test person was measured by a gas meter and analyzed chemically for CO2 and O2.
The Douglas bag was used extensively in field tests, even in boxers.
The company Collins built its first treadmill for the Harvard Fatigue Laboratory.
In 'Methods in pulmonary physiology' a schematic for Dethloff's device was published. This device measured the difference in volume before and after CO2 absorption in order to calculate CO2 output. 2 gazometers, one proximal and one distal in the circuit, were used to achieve this.
The Rebreathing Apparatus of American Physiology Professor Lawrence Henderson (1878-1942) in Harvard was used to test the aptitude of pilots at high altitudes.