BIOLOGICAL ENERGETICS 427 



needed above the basic metabolic level depends almost exclusively on 

 muscular activity. Representative figures for various types of activity ^ 

 are given in Table 16-5. An approximate idea of the total daily energy 



Table 16-5 



Total energy expenditure under dilTerent conditions of musriilar activity * 



Calories per hour 

 Per 70 kg. 



Form OF ACTivriY (Av. Man) Per kg. Per lb. 



Sleeping 65 0.93 0.43 



Awake, lying still 77 1.10 0.50 



Sitting at rest 100 1.43 0.65 



Standing relaxed 105 1.50 0.69 



Dressing and undressing ' 118 1.69 0.77 



Typewriting rapidly 140 2.00 0.91 



Walking, 2.6 mph 200 2.86 1.30 



Carpentry work '. 240 3.43 1.56 



Walking, 3.75 mph 300 4.28 1.95 



Sawing wood 480 6.86 3.12 



Swimming 500 7.14 3.25 



Running, 5.3 mph 570 8.14 3.70 



Walking upstairs 1100 15.8 7.18 



* Reproduced by permission from Sherman, Chemistry of Food and Nutrition, 7th 

 ed., The Macmillan Company, New York, 1946, p. 189. 



requirement might be obtained from these figures by estimating the time 

 spent in various ways. However, more accurate estimates can be made 

 by other methods. If, for example, an exact record of the total food 

 intake of an individual is kept for a period of several months, and the 

 body weight does not change appreciably during that time, the number 

 of calories consumed per day must have been very nearly equal to the 

 energy requirement. Another method is to measure oxygen consumption 

 while the subject is engaged in various activities. Recommended allow- 

 ances based on these and other types of measurements have been made 

 by the Food and Nutrition Board of the National Research Council and 

 are listed in Table 16-6. Note the relatively high allowances for growing 

 children and the increased requirements caused by pregnancy and lacta- 

 tion and by heavy muscular work. 



Obesity. The problem of obesity, or excessive fatness, is unfortunately 

 a very common and serious one in many of the more prosperous, indus- 

 trialized countries. The implications for health, longevity, and general 

 well-being are too well known to require comment. However, the basic 

 facts regarding control of body weight are apparently not well under- 

 stood by many people. 



^ Note fliat til? values in Table 10-5 are for total energy expenditures under various 

 conditions, i.e., they include the basal enerjiy requirement. 



