222 THE PHYSIOLOGY OF MUSCULAR WORK 



man who takes enough active exercise does not overfeed and be- 

 come corpulent, even if the supply of food is unlimited ; his 

 appetite is the expression of the needs of his body, and when these 

 are satisfied the desire for food ceases. 



The digestion and assimilation of the food involve the activity 

 of the alimentary canal and its various glands. Muscular work 

 produces hunger, and " hunger is the best sauce " ; healthy exercise 

 enables a man to enjoy and digest food which otherwise he could 

 not eat. Pity for the labouring poor on account of the plainness 

 of their fare is misplaced. 



The muscles are thrown into activity in response to various 

 impulses, and in this way the whole of the nervous system, in- 

 cluding the special senses, is influenced by muscular work. It is 

 not a question of the discharge of motor impulses alone, but a 

 general effect upon the whole system, so that a man overwrought 

 by sedentary mental work often finds the best restorative in 

 .muscular exercise. 



The respiratory system is thrown into greater activity to supply 

 the increasing demand for the intake of oxygen and the discharge 

 of carbon dioxide. The heart and the vaso-motor system must 

 likewise respond with increased activity to maintain an adequate 

 supply of blood and to adjust the flow to the different organs 

 according to their relative needs. The sweat glands are stimu- 

 lated by the increased heat of the body, and the kidneys will 

 be influenced by the waste products of muscular activity and 

 digestion. 



It may be said that it is unnecessary to lay so much stress upon 

 the value of muscular activity. It is not so. The benefits of 

 muscular work cannot be overestimated. It is a physiological 

 need of a primitive kind, and cannot be eliminated by civilisation. 

 If all men were well worked and well fed many of the great social 

 problems of the present day would be solved. Physiological 

 truths might be carried with advantage into the consideration of 

 social questions. Would there be any danger to the race if those 

 who did not work were not well fed ? Do not those who have 

 not to earn their bread show their recognition of the virtue of 

 muscular work by their devotion to manly sports ? 



Muscular exercise is a necessary condition of a healthy exist- 

 ence ; it is difficult to find the man who has been injured by 

 muscular work, it is easy to procure many who have been ruined 



