The method used in these studies to determine the heart's functional capacity consisted briefly in the deductions made from frequent measurements of the pulse and systolic blood pressure after increasing amounts of work as described in a former article.1 When the highest blood pressure was noted immediately after work and then quickly subsided this work was considered to have been within the heart's capacity. When, on the other hand, the highest pressure was reached a minute or two after the completion of work, at a time when the pulse had dropped back towards normal, that work was regarded as having overtaxed the heart.
Graduated work was furnished in a few experiments by a bicycle ergometer of the type described by Krogh and Linhard,2 but in the majority of cases by movements of flexion, extension and swinging with iron dumb-bells weighing from 3 to 20 pounds each.
BARRINGER TB. STUDIES OF THE HEART'S FUNCTIONAL CAPACITY AS ESTIMATED BY THE CIRCULATORY REACTION TO GRADUATED WORK. Arch Intern Med (Chic). 1916;XVII(5):670-676. doi:10.1001/archinte.1916.00080110083007