THE CIRCULATION 55 



HYGIENE OF THE CIRCULATION 



Care of the Heart. The heart, consisting largely of 

 muscle, is subject to the laws of muscular exercise. It 

 may be injured by over-exertion, but is strengthened by a 

 moderate increase in its usual work. 1 It may even be sub- 

 jected to great exertion without danger, if it be trained by 

 gradually increasing its work. Such training, by giving 

 {he heart time to gain in size and strength, prepares it for 

 tasks that could not at first be accomplished. 



In taking up a new exercise requiring considerable exer- 

 tion, precautions should be observed to prevent an over- 

 strain of the heart. The heart of the amateur athlete, 

 bicyclist, or mountain climber is frequently injured by 

 attempting more than the previous training warrants. 

 The new work should be taken up gradually, and feats 

 requiring a large outlay of physical energy should be at- 

 tempted only after long periods of training. 



Since the heart is controlled by the nervous system, it 

 frequently becomes irregular in its action through condi- 

 tions that exhaust the nervous energy. Palpitations of the 

 heart, the missing of beats, and pains in the heart region 

 frequently arise from this cause. It is through their effect 

 upon the nervous system that worry, overstudy, undue 

 excitement, and dissipation cause disturbances of the heart. 

 In all such cases the remedy lies in the removal of the 

 cause. The nervous system should also be " toned up " 

 through rest, plenty of sleep, and moderate exercise in the 

 open air. 



Effect of Drugs. A number of substances classed as 

 drugs, mainly by their action on the nervous system, pro- 



1 Active exercise through short intervals, followed by periods of rest, such as the 

 exercise furnished by climbing stairs, or by short runs, is considered the best means 

 of strengthening the heart. 



