Military training / by Henry G. Beyer.

  • Beyer, Henry Gustav, 1850-1918.
Date:
[between 1880 and 1889]
Catalogue details

Licence: Public Domain Mark

Credit: Military training / by Henry G. Beyer. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    While, in climbing, the amount of C02 exhaled is ten times that while sleeping, we ought also to breathe ten times more rapidly than we do while sleeping, which would make 10 X 12 = 120 times. But breathing while sleeping is very superficial, which is, of course, not the case during a steep climb, when our whole lung area is engaged in the exchange of gases. We experience, as the effects of training, especially of running, an enlargement of our lung capacity, which normally varies from three to six liters. Heart.—The relation of the heart to muscular work is similar to that which the lung has; it also must answer to an increased demand for work by more numerous and more voluminous con- tractions than it makes during rest, for much more blood flows through the muscles in a given time. To this must be added the increased resistance which the contracted muscles oppose to the flow of blood through them, resulting in an increased general blood-pressure, which the heart must sustain. The greater the muscles and the larger their number engaged, the greater also must be the resistance opposed to the blood-flow, and the greater, consequently, the increase in blood-pressure to be overcome. While respiration is aided by the muscles of respiration which are skeletal muscles, and under the control of the will, the mus- cular action of the heart is perfectly independent of our will. In the main, however, both the heart and the lungs in their action are governed primarily by the want and the necessity for the exchange of gases in the blood. Want of oxygen and over- accumulation of carbon-dioxide in the blood and the tissues generally stimulate the automatic nerve-centres of the heart to greater activity, and the number of contractions may thereby be enormously increased, until, in some cases, the heart-beats are three times their normal number. Just as was the case with the lungs, abnormal rapidity of con- tractions on the part of the heart must sacrifice the thoroughness of its work. When the heart beats at the rate of 160 times per minute, the ventricles contract before they are half full with blood; the pulse, though rapid, is small and feeble, for the arteries are incompletely distended. The contractions of the heart itself are incomplete, being inadequate to the demands put upon it, and consequently we have as a result a momentary insufficiency of the heart, which, however, given a certain period of rest, returns