Rate of Work When you walk very fast, you may feel tired before 

 you have gone a mile. If you walk slowly enough (but not too slowly), you 

 may walk ten miles without showing signs of fatigue. Getting tired is not 

 altogether a question of what kind of work we are doing, nor of how much. 

 It is partly a matter of how fast we are doing it. "It is the pace that kills" 

 (see illustration, p. 225). Physiologically this means that (1) at a certain 

 rate or speed, lactic acid and perhaps other fatigue substances are formed 

 faster than they can be removed by the blood, and from the blood by the 

 kidneys, etc.; and (2) when work is done at a certain slower speed, the 

 blood can remove the wastes just as fast as they are formed. This principle 

 has its everyday applications in athletics, in play, in housework, in school- 

 work, and in industry. 



Fatigue and Efficiency In emergencies men and women exert them- 

 selves to the point of exhaustion. When we manage our own time and 

 efforts, we sometimes find it expedient to work under great pressure, expect- 

 ing to even up the organism's account later. In managing other people's 

 work and time, the problem and the motives are essentially different. But 

 studies made by engineers and physiologists have shown that in the long 

 run the greatest output of work is possible only where fatigue is system- 

 atically avoided. 



It is difficult to observe the maxim "Make haste slowly" when we are 

 eager to get as much as possible from the work of others. People can endure 

 a spell of exceptional exertion if it seems necessary, but everybody hates to 



A MACHINE FOR MEASURING WORK CAPACITY AND FATIGUE 



The ergograph measures and records the frequency and the strength of a pull ex- 

 erted by a finger while the rest of the hand is held firmly in place, in the record, 

 the heights of the vertical lines indicate the relative amount of energy output for 

 each pull on the ring. The distances between vertical lines correspond to the time 

 intervals between pulls 



223 



