THE MUSCULAR SYSTEM 415 



the education of muscles in the importance of momentary rest 

 following contraction, while the peculiar innervation of muscles, 

 known as ' reciprocal,' is also improved by education, and ensures 

 that antagonistic muscles offer little or no resistance to their 

 opponents. 



There is additionally another factor of supreme importance in 

 training. The respiratory movements, as we have learnt, are 

 dependent upon the rhythmic activity of the respiratory centre 

 (p- ^S)- Hence this centre must be taught to withstand the 

 extra strain imposed upon it during violent exertion. What the 

 centre has to ' learn ' in respect of this is more or less a matter 

 of conjecture. Bearing in mind the powerfully stimulating 

 influence on the respiratory centre of the waste products of the 

 metabolism involved in muscular contraction, it is conceivably 

 possible that ' wind ' is the result of an increased immunity of 

 the centre to the action of these products. However this may 

 be, one thing is certain — namely, that respiratory distress is more 

 potent than most other factors in determining ' staying power,' 

 the one thing to which all long-distance athletes strive to attain. 

 In this connection we may point out that it is said that the 

 deleterious products of metabolism produced during fatigue may 

 be neutralised and immunity established by giving small doses 

 of extracts of a fatigued muscle ; the question has therefore arisen 

 as to whether ' training ' may not be a process of immunising 

 against fatigue products. 



Condition may also be defined as fitness for the class of work 

 required, and one has only to think of the many uses to which 

 horses are put to recognise that what constitutes fitness in one 

 class, and for certain work, is unfitness for another. The 

 circulatory and respiratory features of ' condition ' have been 

 referred to at p. 414 ; these constitute the basis on which the 

 training of the machine is carried out ; but there is something 

 more — there is the special education of the muscles for the 

 particular class of work required. All muscles in the body are 

 not equally conditioned, and this is forcibly brought home when 

 for any reason uneducated muscles have to be employed. If a 

 man uses his left limbs for services in which he always employs 

 his right, his helplessness is at once manifest ; if he employs a 

 group of muscles ordinarily idle, he is surprised at the effort 

 required to extract any work from them and the feebleness of 

 their response. The employment of muscles in this condition 

 is a wasteful process, and until they are educated they cost more 

 and do less work than the trained article. Each muscle has to 

 learn how to perform effective work economically, and each 

 group has to be instructed how to work harmoniously with other 

 members of the group. The only way in which this education 



