In the Harvard Fatigue Laboratory, American physiologist Lawrence Henderson (1878-1942) demonstrated that the efficiency of the cardiovascular system improves through endurance training due to a decreasing stroke volume and a decreasing heart rate at rest.
In the Journal of Biological Chemistry, 1926; 69: 513-517, a portable calorimeter was proposed by American physiologist and chemist Jesse Fransis McClendon (1880-1976), with which both O2 and CO2 could be determined.
German sportsphysician Wolfgang Kohlrausch (1888-1980) is called the father of the German 'Krankengymnastik', which he used for the sicks in several hospitals. He was offered the first Chair in Sports Medicine and in 1926 he opened a gymnastics department of the 'Chirurgischen Universitätsklinik Berlin', of which he was the responsible physician from 1920 to 1935 and also the leader of the anthropometric laboratory of the 'Deutschen Hochschule für Leibesübungen'. He specialized in Sportshygiene and was appointed professor at the Universität Berlin in 1934. From 1935 to 1941 he was the leader of the 'Sportmedizinischen Instituts' at the 'Medizinischen Fakultät der Universität Freiburg' and from 1941 to 1944 Ordinarius für Bewegungstherapie at the 'Reichsuniversität Straßburg'. After a year of imprisonment, he became a teacher at the Physiopraktikerschule am Kantonsspital Zürich and from 1954 to 1959 he led the Hohenfreudenstadt sanatorium.