Validity of Ergograph as Measurer of Work Capacity 9 



more rapid, making less the actual loss from each discharge. 

 The cumulative effects of the discharges in a long series would 

 be rhuch slower in reaching the point where further functioning 

 would be impossible. 



Changes in the character of circulation in the muscle take 

 place as a result of exercise. It is a well-known fact that activity 

 in a muscle increases immediately the amount of blood that flows 

 to it, and it is probable, further, that systematic and continued 

 exercise will increase the possibilities for the amount of blood 

 flowing into the muscle. Capillaries may be enlarged and thus 

 the tissues will be washed by a greater flow of blood, insuring 

 a more rapid elimination of the waste products accumulating 

 through exercise, and at the same time furnishing a greater sup- 

 ply of oxygen to carry on the process of combustion within the 

 tissues. Therefore during the interval between each successive 

 contraction, the accumulated waste will suffer a greater reduction 

 in amount, and more extensive rebuilding of the protoplasm will 

 take place. For this reason the muscles may make a larger num- 

 ber of contractions before the waste products accumulate to the 

 point where they have a paralyzing effect on the muscle tissues, 

 and through the rebuilding of the tissues a larger amount of 

 protoplasmic substance remains at the disposal of the muscle, 

 from whose disintegration the energy for the contraction of the 

 muscle is supplied. 



The nerve centers, too, probably enjoy an increased circulation 

 as a result of their continued activity. The accumulation of waste 

 products in the centers will thus be kept down below the toxic 

 point for a longer period, and the recuperation of the cells between 

 successive explosions will more nearly equal the amount of 

 exhaustion occasioned by the explosion, so that a large number 

 of explosions are made possible before the point of paralysis is 

 reached. 



The lower nerve centers are automatic and recuperate com- 

 pletely between successive discharges, so that they can go on 

 throughout life w r ith no cessation of activity ; they enjoy com- 

 paratively few and slight accelerations and suffer few and slight 

 depressions. Nerve centers with regard to rhythmical activity 



87 



