INTELLIGENCE, POWER, 



"Most important for cardiac load, however, is the fact 

 that body efficiency declines as the combustion rate in- 

 creases. During winter cold a given amount of physical 

 work costs more in terms of oxygen consumed and heat 

 and energy expended than it does in summer heat. A 

 hyperthyroid person pays a higher metabolic price for the 

 execution of a piece of work than does a normal person. 

 Tropical natives are far more efficient physically than are 

 the energetic northerners, remembering that efficiency refers 

 to the energy cost per unit of work accomplished. Differ- 

 ences in energy cost may be quite striking and play an 

 important part in making heart failure so much more 

 common during the colder portions of the year. These 

 findings on the metabolic cost of work have failed to receive 

 the attention they deserve in regard to the growing prob- 

 lems of the heart. People not only feel more energetic in 

 cold weather and move around more quickly to keep warm, 

 but each move they make carries a higher metabolic and 

 heart work cost. 



"Herein lies the main reason why cardiac failure is so 

 much more common in winter than in summer. 



"Of particular interest in this connection was the wide- 

 spread fall in blood pressure and oxygen consumption level 

 that took place during the severe and prolonged heat 

 afflicting the Middle West in the summer of 1934. In a 

 goodly proportion of the population blood pressures 

 dropped about 30 per cent from whatever level had pre- 

 viously obtained. Relief from cardiac symptoms was espe- 

 cially marked in h) pertension cases as the general body 

 metabolism fell to low levels. This experiment on climatic 

 effects, staged by Nature, gave striking substantiation to 

 our ideas previously stated, and indicated in no uncertain 

 way the shift toward tropical metabolism that can be 

 brought about in a highly energetic population mass by only 

 a few weeks of severe warmth." 



William F. Petersen, in his study of "The Patient and 



244 



