426 BIOLOGY FOR BEGINNERS 



Health is the natural condition of the body, and yet, how many 

 have never been sick, or are now in absolutely perfect health. We 

 must remember that any lack of health is due to some biologic 

 mistake. While we can probably never know enough to absolutely 

 avoid disease certainly our study of biology ought to help us to 

 escape those troubles whose causes we do know. If we lived as 

 well as we knew how, everybody would be much stronger, healthier, 

 and happier. It is to call attention to some of the simpler ap- 

 plications of biology to health, that this chapter is written. 



Hygiene of the Muscles. A great deal is being done with re- 

 gard to proper muscular exercise and it is well to understand some 

 of the reasons for the importance of this matter. The least impor- 

 tant result is one most often mentioned, namely the fact that ex- 

 ercises strengthen the muscles used. This is true but the following 

 results are much more important to health. 



1. Exercise increases oxidation, from three to ten times; this 

 means that greater bodily energy is liberated. 



2. From this it follows that the heat-regulating and excretory 

 organs are trained to their work. 



3. Exercise withdraws the blood from the internal organs, to the 

 muscles and so relieves the tendency to over-supply and conges- 

 tion; this is shown by the " healthy color " of the complexion due 

 to the blood supply in the outer muscles; a very pale skin usually 

 indicates poor health. 



4. Only by proper exercise do the heart and arteries receive 

 necessary training in supplying the blood to the tissues. 



5. In the same way, exercise aids in the use and health of the 

 lungs and breathing organs. 



6. Motion of the muscles is one of the chief causes of lymph 

 flow and we know that upon the lymph circulation depends the 

 nutrition of the tissues. 



No rules can be given as to special kinds of exercise, since dif- 

 ferent people need different forms, just as we need different amounts 

 of food, but in general it may be said that any exercise should 

 bring about the results mentioned above, and should not be such 

 as to endanger or overstrain any part of the body. 



