378 THE POPULAR SCIENCE MONTHLY 



and viscera. He uses up the oxygen in the arterial blood more com- 

 pletely and with greater efficiency; for the output of each unit of 

 energy his heart has to circulate much less blood (Kreogh) ; his 

 blood is sent in full volume by the well-balanced activity of his vaso- 

 motor system to the moving parts. Owing to the perfect coordina- 

 tion of his muscles, trained to the work, and the efficient action of his 

 skin and cutaneous circulation — the radiator of the body — he per- 

 forms the work with far greater economy and less fatigue. The un- 

 trained man may obtain 12 per cent, of his energy output as work, 

 against 30 per cent, or perhaps even 50 per cent, obtained by the 

 trained athlete. Hence the failure and risk suffered by the city man 

 who rushes straight from his office to climb the Alps. On the other 

 hand, the energetic man of business or brain worker is kept by his 

 work in a state of nervous tension. He considers alternative lines of 

 action, but scarcely moves. He may be intensely excited, but the 

 natural muscular response does not follow. His heart is accelerated 

 and his blood pressure raised, but neither muscular movements and 

 accompanying changes of posture, nor the respiratory pump materially 

 aid the circulation. The activity of his brain demands a rapid flow 

 of blood, and his heart has to do the circulatory work, as he sits still 

 or stands at his desk, against the influence of gravity. Hence a high 

 blood pressure is maintained for long periods at a time by vasocon- 

 striction of the arteries in the lower parts of the body and increased 

 action of the heart; hence, perhaps, arise those degenerative changes 

 in the circulatory system which affect some men tireless in their 

 mental activity. We know that the bench-worker, who stands on one 

 leg for long hours a day, may suffer from degeneration and varicosity 

 of the veins in that leg. Long continued high arterial pressure, with 

 systolic and diastolic pressures approximately the same, entails a 

 stretched arterial wall, and this must impede the circulation in the 

 vaso vasorum, the flow of tissue lymph in, and nutrition of, the wall. 

 Since his sedentary occupation reduces the metabolism and heat pro- 

 duction of his body very greatly, the business man requires a warmer 

 atmosphere to work in. If the atmosphere is too warm it reduces his 

 metabolism and pulmonary ventilation still further; thus he works in 

 a vicious circle. Exhausting work causes the consumption of certain 

 active principles, for example, adrenalin, and the reparation of those 

 must be from the food. To acquire certain of the rarer principles 

 expended in the manifestation of nervous energy more food may have 

 to be eaten by the sedentary worker than can be digested and metab- 

 olized. His digestive organs lack the kneading and massage, the rapid 

 circulation and oxidation of foodstuffs which is given by muscular 

 exercise. Hence arise the digestive and metabolic ailments so com- 

 mon to brain workers. 



