286 MUSCLES 



allow the weights to exceed a certain limit. In oui' bodies 

 a healthy muscle is always in this state of elastic tension, 

 as is shown by its shortening when the tendon which 

 attaches it is cut. This tense condition makes the muscle 

 respond much more quicklj^ to stimuli, and is of great 

 value in mechanical movements of the body. Muscles 

 which are not used tend to lose this elastic tension and to 

 become soft and flabby. The only method of remedy is 

 to give them plenty of use or exercise. Exercise, there- 

 fore, is of value in keeping our nmscles in a proper state 

 of tension, and, at the same time, aids in the proper cir- 

 culation of food and oxygen material to the used parts. 

 Care should be taken in the selection of the exercise that 

 it shall affect all the muscles of the body and not center 

 upon any one set of muscles. Rowing and rurming are 

 particularly valuable as forms of exercise which call into 

 play many muscles; and walking is one of the best forms, 

 since it exercises the body and leg muscles and the lung 

 and heart muscles, and is not violent enough to over- 

 fatigue any given set. "\\1iat are called " setting up " 

 exercises in the army and in our schools are particularly 

 good, since they have been devised to fit every part of the 

 body and to give a general toning up of the system rather 

 than to develop any one set of muscles. 



Another feature of exercise that should be borne in 

 mind is that it should be regular. A little regular exer- 

 cise each day, calling into play as many muscles as pos- 

 sible, is far more valuable than prolonged exercise one day, 

 followed by a long period of no exercise. Further, since 

 active muscle makes gi-eat demands upon the blood supply, 

 we should not exorcise immediately after eating when the 

 blood is needed elsewhere. 



