1917 Archives of Internal Medicine  
The term functional capacity is used to indicate the total amount of power possessed by the heart muscle. When the body is at rest a small portion of this power is utilized to furnish the circulatory requirements of the metabolism. As soon as any muscular activity occurs the so-called reserve power of the heart is drawn on to furnish blood to the working muscles. Of these two component parts of the power inherent in the heart muscle the reserve power forms normally by far the larger portion,
more » ... larger portion, and it is with this factor that our studies are concerned. We propose to gain an idea of the heart's functional capacity by a measurement of its reserve power. The method used to determine this is based on the circulatory reactions to graduated work, and a rather detailed description of these reactions is necessary to a clear understanding of our test, and, what is more important, to a belief in its validity. Work was furnished by means of a Krogh-Lindhard ergometer in a few experiments, but in the greater number by movements with dumb-bells. The blood pressures were taken by the auscultatory method with a Riva Rocci manometer. A rubber hand bulb was used to inflate the cuff. The systolic pressure and pulse were taken and then work was performed. The pressure was read again between twenty and thirty seconds after completion of work. This was the time required with our technic to make the first reading, and 90 per cent, of the readings on the first trial fell between 20 and 30 seconds. If the first reading was made before twenty seconds or after thirty seconds had elapsed the experiment was discarded. A second reading was made between 50 and 60 seconds after work, the aim being to make it as close to 60 as possible, and the third reading 90 seconds after. Then readings were made every 60 seconds. (In our earlier experiments we made readings every 60 seconds after the first reading; later we made readings every 30 seconds after.)
doi:10.1001/archinte.1917.00090060003001 fatcat:oqmrcqjf6vbjbc2lv3qoy7a4qi