Early in the war, Sir James Mackenzie1 proposed that in the examination of the hearts of applicants for military service more stress be laid on how the heart responds to effort. He says that if the applicant can undergo severe bodily exertion without distress, it is fairly safe to assume that any irregularity or systolic murmur present is without significance. This is not new, but it lends great emphasis to the examination of the circulatory apparatus as a whole and to judging a heart by the circulation it can maintain. Heretofore, cardiac examination has concerned itself principally with detecting imperfect valves, sclerotic arteries, and dilated or hypertrophied myocardium. The function tests were developed to detect inefficiency of the heart in maintaining the circulation and impending heart failure.
In 1915, Swan2 reviewed the heart function tests proposed up to that time. Tigerstedt, Stone, Goodman and Howell, and many others