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Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
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Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
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Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
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Page 53
Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
×
Page 54
Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
×
Page 55
Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
×
Page 56
Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
×
Page 57
Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
×
Page 58
Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
×
Page 59
Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
×
Page 60
Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
×
Page 61
Suggested Citation:"Metabolic Rates for Military Activities (Wulsin)." National Research Council. 1945. Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.). Washington, DC: The National Academies Press. doi: 10.17226/18651.
×
Page 62

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52 CLOTHING TEST METHODS however closely we may estimate average loads, there is no telling what extremes of exertion may be demanded of some individuals. Second, little adjustment for temperature is possible. The soldier usually has to go through the fight with what he has on when it starts, and he is sure to be too hot or too cold a large part of the time; thus a thermal stress is added to the stress of exertion. Third, the soldier may remain in combat for days or weeks, working and fighting with little or no unbroken rest, often with scanty food at irregular hours, per- haps at times with insufficient water. Finally, his activities are carried on to an accompaniment of loud noises and concussions, he is surrounded by gruesome sights, and he is continually under the nervous and emotional strain of imminent danger. The first three of these combat conditions can perhaps be approximated in the laboratory. The last can hardly be duplicated away from the actual battle- field, yet battles are won or lost by the endurance of troops, as much as by any other factor. It is therefore desirable to examine the nature and magnitude of the stresses peculiar to combat, and to determine If possible their bearing on the selection of army clothing, rations and equipment. The possibility of re- producing them in the laboratory can then be considered. Section II It is clear, from the preceding section, that the total stress on the soldier can be considered most conveniently under two headings: first, work load, in the sense of muscular exertion, whether steady or fluctuating; and second, extra stress due to long hours of work, insufficient sleep, sometimes insuffi- cient food or water, and danger. Work load will be discussed in this section, and extra stress in section III. Numerous determinations of the metabolic rates connected with various civilian occupations are available. These can frequently be applied to army problems. In addition, the Harvard Fatigue Laboratory has made direct measure- ments of the caloric expenditure of soldiers during various military activities.! The results are given in Table I. In interpreting them, the following points should be borne in mind: (l) The determinations were made in June, 1943, at Camp Lee, Virginia. The weather was hot. (2) The figures have been reduced to values for a 150-lb. man. (3) The weight of clothing worn was about 7-1/2 lbs. (4) Full equipment, when specified in the table, weighed a total of 18 lbs. 10 oz. This weight was made up as follows: Belt, Cartridge, Cal. .30, Dismounted, M-1923 1 Ib. 10 oz. Ammunition, Cal. .30, Rifle, 80 Rounds 5 0 Canteen, Filled with Water, with Cup and Cover 3 10 Packet, First Aid, with Pouch 6 Helmet, Steel, with Liner 3 0 Gas Mask, Service, Complete 5 0 18 lbs, 10 oz. The Bayonet with Scabbard (l lb. 8-1/2 oz.) and the Intrenching Shovel with its Carrier, (2 lbs. 3-1/2 oz.) were carried on the pack and are therefore included in its weight. The Rifle, M-l, weighs 9 pounds. 1. Report to the Surgeon General's Office, July 12, 19^3, entitled "Comparison between estimates of caloric expenditure of soldiers as obtained by calculations involving standard values and as obtained by direct measurement in the field," by R. £. Johnson, G. C. Pitts, and Major H. Pollach, M. C., with the technical assistance of Pfc. J. Stachelek; from the Harvard Fatigue laboratory, Harvard University, and the Quartermaster Board, Camp Lee, Virginia. The writer is indebted to Dr. Johnson for permission to reproduce the figures given in tables I and II and for much other assistance.

, METABOLIC RATES FOR MILITARY ACTIVITIES 53 Table I CALORIC EXPENDITURE OF A 150-POUND SOLDIER DURING VARIOUS TYPES OF ACTIVITY Energy expenditure measured by Harvard Fatigue Laboratory Description of Activity Cals/hr. 1. Marching on level with JO-lb. pack, rifle and full equipment; 50 mins. of marching and 10 mins. rest, covering 3 miles 410 2. Similar marching and equipment, but with 50-lb. pack 457 3. Field rushes with full equipment (repetition of 5 secs, running, 10 secs, lying prone). One hour consists of 10 mins. march to area, 40 mins. rushing in which 15 mins. is spent rushing and 25' spent lying prone. 10 mins. rest at end 415 4. Creeping and crawling with full equipment.' One hour consists of 20 mlns. marching, 10 mins. resting, 7-1/2 mins. creeping, 7-1/2 mins. crawling both high and low, with 15' of prone resting 405 5. Obstacle course with light pack and rifle. Course lasts about 5 minutes and consists of pit jump, hurdles, log crossing, ditch jump, maze run, log step climb, ditch climb up and down, 12-foot landing net climb, high tunnel run, log ladder up and down, broken field run, low tunnel crawl, rope swing, high fence climb, one log sitting bridge, walking log bridge, and parapet ditch jump. One hour consists of 20 mins. marching, 2 circuits of course and 20 mins. rest 380 6. Digging fox holes. Two hours consists of 20 mins. march, eighty minutes of digging (half the time spent resting) followed by 20-min break 240 7. Field fortification, - continuous digging 325 8. Calisthenics: 1/2 hour consists of 15 mins. standing about and 15 mlns. activity including 1 min. running in place, 50 side straddle hops, 48 squat hops, 15 pushups, 50 knee-bends, 10 mins. of light arm exercise 300 9. Close order drill—presumably rifle only 200 10. Rifle exercises, 1/2 hour consists of 15 minutes of standing about, and 15 mins. of exercises including 32 squat hops with rifle above head, 36 side lunges with rifle and other exercises as in 8, but with rifle 450 In the course of the same study, the total energy expenditure per day of a 150-lb. soldier in the training regiment at Camp Lee was established by the Harvard Fatigue Laboratory for 2 sample days, using the measured metabolic rates given above, supplemented where necessary by rates from other sources. The re- sults are given in Table II. Dr. Johnson, who conducted the tests at Camp Lee, points out that the soldiers attended to all their personal errands, chores, and diversions in the periods marked "rest" and "off duty," and that the metabolic rates for those periods as given in the Table, and consequently the totals, are somewhat too low.

54 CLOTHING TEST METHODS It should be noted also that the total caloric expenditure for the second sample day is greater than the amount of energy contained in the B ration, a point of considerable importance in experiments which bear on the adequacy of army rations. A confirmation of the metabolic rates for marching with a load which are given in Table I is found in the work of Brezina and Kolmer, which was published in 1912. Brezina's metabolic rate was determined while he walked with different loads at different speeds. The results have been plotted in Fig. 1, in such a way as to show energy expenditure per hour marched and also per mile, at differ- ent speeds and with different loads. Brezina weighed 155 Ibs., the loads g^ven are exclusive of clothing worn, and the values are for a whole hour of marching, not for 50 minutes of marching and 10 minutes of rest, as in the case of the figures in Table 1. When allowanace is made for these factors, the graph shows good agreement with the measurements made by the Harvard Fatigue Laboratory at Camp Lee. The figures in Tables I and II are for a 150-Ib. man, and the values in Fig. 1 are for a 155-lb. man. It is appropriate to ask whether the results would be different for men who are heavier or lighter. Does the metabolic rate at work depend primarily on the task, the surface area of the subject, or the weight of the subject? Here experimental evidence is available, which shows that one must distinguish between activities in which a man moves his whole body, such as marching, digging, etc., and those in which the body weight is sup- ported and only a few groups of muscles are used, such as riding a stationary bicycle. Winslow and Gagge2 have shown that the increase in metabolic rate dur- ing work on a stationary bicycle is not related to body weight, but only to work output on the ergometer. Most military activities, however, and especially the activities of combat, involve moving the whole body. Robinson has shown that in this case metabolism is proportional to body weight.3 He measured the metabolism of two excellent athletes who walked and ran at the same speed under conditions of severe heat stress. One of the men weighed 61 kilograms and the other 99 kilo- grams. The results are given in Table III. It is obvious from these data that the men's metabolic rates at a given rate of walking were proportional to body weight. The purpose of Robinson's experiment was to determine the influence of body size upon a man's ability to dissipate heat. Heat production, when walking or running, proved to be a function of body weight, whereas heat dissipation is a function of surface area. Therefore, the heavier man with 44 kilograms of body weight per M2 of skin surface was unable to maintain thermal balance in the more severe experiments, whereas the lighter man, who had only J>6 kilograms of body weight per M2 of skin surface, was able to remain in thermal balance throughout. Thus total mebabolism varies directly with body weight, for activities which involve moving the whole body. When a man carries a pack of moderate weight, up to about 20 kilograms, his total metabolism goes up by the same amount as if his body weight had been incre'ased to equal his actual weight plus the weight of the pack. In other words, it does not matter whether the load is tissue or baggage; the metabolic cost of carrying it is the same4. When heavier weights are carried the expenditure of energy per kilogram is increased; the same is true when the maximum economic velocity of walking, which is about "$ miles per hour, is exceeded. These relationships are apparent in the curves of Fig. 1. 2. Am. J. Phyeiol. 134: 664, 1941. 3. Botinson, S. "The effect of body size upon energy exchange in work" Am. J. Physiol. 136: 363, 1942. 4. Luak "Science of Nutrition," 4th Edition, 1928, p. 431, quoting Brezina and Sechel, Bio-chem. Z., 1914, 63, 170.

METABOLIC RATES FOR MILITARY ACTIVITIES 55 Table II CALORIC EXPENDITURE DURING TWO SAMPLE DAYS (150-POUND SOLDIER) Time 5 AM 5:10 5:15-5:45 5:45-6:00 6:00-6:30 6:30-7:30 7:30-8:30 8:30-9:30 9:30-10:30 10:30-11:30 11:30-12:0 PM 12:00-12:45 12:45-2:45 2:45-3:45 3:45-4:45 4:45-5:15 5:15-5:30 5:30-6:15 6:15-7:15 7:15-8:15 8:15-9:30 9:30-5:0 AM 5 AM 5:10 5:15-5:45 5:45-6:00 6:00-6:20 6:20-6:45 6:45-11:45 11:45-12:0 PM 12:00-12:20 12:20-1:15 1:15-4:15 4:15-5:30 • 5:30-5:50 5:50-9:30 9:30-5:00 AM Activity Value calculated from generally accepted figures in literature (Calories) 1st Sample Day 1st call Reveille Calisthenics Rest and fatigue duties Breakfast Calisthenics with rifle Creeping and Crawling Field march without eqpt. or gear Obstacle course Field march, without eqpt. or.gear Rest and fatigue duties Dinner Rest and fatigue duties x Light activities Boxing and Wrestling Light activities Rest and fatigue duties Supper Close order drill Calisthenics with rifle Fatigue duties Bed Totals 2nd Sample Day 1st call Reveille Calisthenics Rest and fatigue duties Breakfast Fatigue duties Road march Fatigue duties Dinner Rest and fatigue duties Road march Fatigue duties Supper Off duty in area Bed Totals Value, measured or customarily used by Harvard Fatigue Laboratory (Calories) 25 150 25 55 450 305 310 380 310 50 85 200 120 350 60 25 85 280 450 190 525 4430

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METABOLIC RATES FOR MILITARY ACTIVITIES 57_ Robinson has measured the effect of weight of footgear on metabolic rate In marching. He found that the energy requirement for carrying 1 kilogram of weight added to a man's shoes is as great as for carrying 4 kilograms added to his pack. In this connection, the effect on the energy cost of marching,of dif- ferent kinds of terrain, and of different types of pack, also deserve study. In selecting tasks to represent the activities of the soldier, one must remember that the amount of marching and the weight carried vary from one theatre of operations to another, and change also within any given theatre, with the tactical situation and the amount of transport available. In the campaigns of the British 8th Army in North Africa, men were carried long distances' in trucks and marched relatively little, except in the immediate vicinity of the battlefield. In combat they usually carried only weapons, rations, and an absolute minimum of personal gear, making a total load of 30 to 40 lbs.e In the New Guinea campaign, the Australian soldiers who crossed the Owen-Stanley Range carried 51 Ibs. 10 oz. of clothing, equipment, rations, ammunition and personal armament, plus a share of extra ammunition and heavy weapons, averaging 20 to 50 Ibs. per man. Even so, the amount of clothing and food that they carried was the bare minimum for ex- istence. The trails were bad, with a constant succession of steep hills and gullies, and the footing was deep mud mixed with roots. The going was so arduous when climbing steep grades that men usually moved forward for 20 minutes and then rested for 10. Such work is far more exhausting than ordinary marching. In assessing the burdens imposed upon the soldier in this sort of campaign, and the metabolic rates to represent them, the elements of cumulative fatigue and malnutrition must be considered. The Australians in the Owen-Stanley Mountains received a daily ration containing about 1900 calories, with irregular supple- mentary issues which brought the total up to about 2500 calories, and were in con- stant touch with the enemy. As a result of their hardships, these men lost 20 to 30 Ibs. in 8 to 10 weeks. A discussion of the effect of such extra stresses on metabolic rates is found in the next section. Section III The extra stresses which fall on the soldier in the field can be given tentative classification under the following headings: (l) Exposure to heat and cold; (2) long hours of work; (3) insufficient sleep; (4) insufficient food or water; (5) danger. Thanks largely to the work on arctic and tropical clothing, on diet for soldiers, and on related problems, which has been done under the direction of the Oommittee on Medical Research, a great deal is known about the effects of heat and cold on the body. Dehydration also has been studied by various agencies.7 As a result, no discussion of these topics in this paper seems necessary. Much less is known about the effects of the other stresses which have been mentioned. In some cases it seems possible that useful quantitative information about them could be gained by laboratory experimentation. It is one of the purposes of this paper to call attention to these opportunities. In examining the effects of extra stress on the soldier, metabolic rate is only one of the quantities in which we are interested. Cumulative fatigue, as measured by decrease in capacity for performance, is fully as important. Some standard task must be chosen, which a man will perform less well or less willingly 5. See Interim Beport Ho. 3 to OSKD, from the Department of Physiology, Indiana University. 6. These figures and those for New Guinea were given to the writer by Major L. E. Dawson, D.S.O., of the Australian Imperial Forces, who participated in both campaigns. 7. Adolph, Armored Medical Besearch laboratory, and others.

58 CLOTHING TEST METHODS when he ia tired than when he is fresh, and which is so arranged that improvement due to practice can be eliminated as a source of error. Since it is well known that there is great individual variation in resistance to fatigue, a man's per- formance under one condition should usually be compared with his own performance under another, or the results for large groups should be averaged. Long Hours of Mark—Long hours of work and insufficient sleep will be discussed together, because they are usually associated in practice. When hours of work are increased, the total metabolism per 24 hours is increased also, if the metabolic rate during work is higher than the metabolic rate during relaxation. Thus the soldier who marches 10 hours expending 400 kg. cal. per hour, will use up more calories and need more food than if he marches 6 hours at this rate, and loafs or strolls for 4 hours at 100,kg. cal. per hour. The effect on food requirements of this increased caloric expenditure is easily calculated. It would be interesting to know whether the amount of sleep which is needed to maintain perfect health is increased also, and whether a quantitative relationship between total caloric output per 24 hours and hours of sleep required can be established. The matter could be tested by observing the amount of sleep taken voluntarily by healthy subjects at moderate and again at severe work levels. Long hours of work do not always involve increased total caloric expendi- ture. For example, the office worker who stays at his post for 12 hours may have a lower total metabolism for the day than if he stayed at his post for 8 hours and then went for a walk or played baseball. Nevertheless he will probably be far more tired, at the end of a month of vorking 12 hours a day, than if he had worked less, exercised more, and had a higher total daily metabolism. Here the relation between hours of work and cumulative fatigue is what we are trying to determine. A measurement of the accuracy and speed with which familiar but skilled operations can be performed would appear to provide a useful test for this purpose. When working hours are abnormally long the total time available for sleep, relaxation and necessary personal chores is reduced. The net effect is usually a reduction in sleep, for some chores cannot be postponed, and men are often more reluctant to give up diversion than to shorten their hours of rest. It is possi- ble that from the point of view of cumulative fatigue the choice is a wise one; this point also should be investigated. It would be advantageous to know how work and rest should be divided, for minimum fatigue, with a given total number of hours work. For example, if men must march 12 hours a day for 4 days, it would be advantageous to know whether it is better to march 4 hours and rest 4, throughout the day and night, or to march 12 hours with 2 one-hour halts for meals, and then rest 10, or to adopt some dif- ferent system. Should meals be small and frequent, or larger and further apart, for such an effort? Is it better to march fast and gain longer rest periods, or the reverse? These questions can be approached in two ways: we can either have the subjects perform a standard task—say a 40 mile forced march in 24 hours— using two different systems of resting or of feeding, and then perform tests on them to measure how tired they are; or we can see how far or how fast they can march, with a given incentive, when each of two systems is used. For example, let the task be a 7-day march and let two teams participate, each team using a particular system of rest or feeding. Every man on the team that marches furthest in 7 days gets a 3-day pass,.and the distance marched is the average for the best three-quarters of the team. In a repetition of the experiment the teams inter- change their systems of resting and feeding, but the same incentive is held out. A few such tests would show which system is best.

METABOLIC RATES FOR MILITARY ACTIVITIES 59 Insufficient food—The effect of total starvation has been studied by a number of workers. The effect of insufficient feeding, that is of caloric intake less than caloric output, has received less attention. Yet soldiers in active combat rarely get adequate meals, and sometimes cannot or will not eat all the emergency rations they carry. Thus underfeeding in the army may arise from one of two causes: sheer breakdown of supply, so that soldiers do not receive enough food to eat; and failure to eat the' food which they do receive, because it has become monotonous or distasteful. Insufficient rations may be issued for fairly long periods, through mili- tary necessity. The situation may nevertheless demand that the soldier perform full military duty, and he will do so as long as he is physically able to, mean- while using up his reserves. It might prove useful to know how long a rate of activity in excess of caloric intake can be maintained, and how long it takes a man, who is well fed after a period of overwork and partial starvation, to come back to his normal weight and strength. Throughout such an investigation two criteria would appear to be useful; body weight, and performance in response to a fixed incentive. Malnutrition which is due to the fact that rations, though supplied, are not eaten, has been discussed by the Harvard Fatigue Laboratory, the Armored Medical Research Laboratory, and others. Here the problem is getting the men to eat the food which has been provided, in spite of the fact that they do not like it, or do not like some components. It would appear to be desirable to examine the practical usefulness of additions which might improve appetite, or in other ways make the food more acceptable. The use of carminatives, relishes, season- ings and alcohol, in forms which could be transported and issued in the field, may be considered. Gain or loss of body weight, when men are doing a fairly large but fixed amount of work on a monotonous and unpalatable diet, will give a simple and direct means of measuring the value of the additions suggested. The experiment should continue long enough, to have the diet of the control group be- come deadly monotonous and almost uneatable. Additions to it, for the experi- mental group, should be very limited in quantity, but should be made with skill and imagination. Danger—Earlier paragraphs have dealt with the physical hardships of campaigning. Here we are concerned with the effects which exposure to danger, as distinguished from physical hardship, may have on a man's metabolism, his need for food and sleep, and his ability to undergo fatigue. A number of psychological stresses, which increase in intensity with approach to the battlefield, are involved. Our problem is, if possible, to find means of measuring the effects of such stresses on the body. For the purposes of this paper, this immensely complex subject can be considered under two headings: the effects of strong emotion in general, and the effect of the conflict, which all or nearly all men feel, between fear and duty. Strong emotion often enables a man to outdo his ordinary physical per- formance. Bock and Dill have discussed this effect in the case of athletes.8 The added performance involves an increase in cardiac accelerator tone, in blood flow, pulmonary ventilation and metabolism; this last involves an increase in heat production and food requirements. While momentary maxima in metabolism may be of no particular importance, as far as overall requirements for food and cloth- ing are concerned, it is quite possible that the metabolic rate is increased significantly over the whole period during which a man remains exposed to danger, even though activity be light; for danger is a stimulus which keeps him intensely alert, and this presumably involves increased muscle tone and blood flow. B. Bainbridge, Physiology of Muscular Exercise, 3rd Edition, Rewritten by A. V. Bock and D. B. Dill, 1931.

60 CLOTHING TEST METHODS To test this hypothesis by measuring metabolic rates on the battlefield seems to be out of the question. To obtain a measure of the metabolic cost of constant strain on the attention, combined with a trace of fear, should not, how- ever, prove too difficult. Let a man ride a bicycle on a broad and safe tread- mill, and again on a narrow, elevated treadmill, where he must be constantly alert to avoid falling off and receiving bruises; let the amount of mechanical work required be the same in both cases, and let metabolism and other relevant quantities be measured. Such an experiment should tell us whether the nervous strain of riding in a slightly dangerous situation increases the metabolic rate, and how much, and thus give some indication of changes in nutritional require- ments which may be brought about by combat. It might give other information also; for instance, one might be able to determine the degree of fatigue brought on by each type of riding, by following the experiment with some test of performance in which fatigue would figure. The measurement of the physical effects of a mental conflict, such as that between fear and duty, is fraught with great difficulties. We do not know what physical effects to look for, and the type of conflict we are concerned with cannot be produced in men in a simulated situation. This suggests the use of laboratory animals, which have been conditioned to mutually exclusive courses of action ±n response to distinc t stimuli. Such animals can be exposed to both stimuli at once, and the relative intensity of the stimuli can be varied, thus producing any desired degree of conflict. Once that situation has been produced, however, one is still faced with the problem of knowing what quantities to measure. Capacity for work suggests itself; but it is already well known, from ordinary human experience, that mental conflict can be exhausting, and to simply confirm this observation by experiments on animals seems hardly worth while. What is desired is information as to the chemical or physiological mechanism involved in producting the exhaustion which is known to occur, when conflict is intense, because mutually exclusive courses of action are desired ardently at the same time. We also want to know what occurs when the stimuli are1 not evenly balanced, so that one course of action is followed and the desire for the other remains unsatisfied. One approach to these questions is suggested below. The psychological mechanism of conflict seems to be, that imagination embraces first one alternative and then theother; but before either one can be followed out, it is inhibited, so that there is a great deal of psychological starting and stopping. May not these mental preparations, always thwarted, involve chemical changes which could be detected by sufficiently refined methods? It is hoped that other and perhaps more valid lines of approach to these problems will suggest themselves to those who may undertake their study.

METABOLIC RATES FOR MILITARY ACTIVITIES 61 ENERGY EXPENDITURE BY 155 Ib. MAN CARRYING A PACK n~g. Ca L. /&e.r hour ed. Kg. Cal. per mile plotted from figures determined by Brezina and Kolmer, 1912, as quoted by Benedict and Murchhauser, 1915 Fig. 1

STATISTICAL CONSIDERATION OF DATA Miss Agnes Galligan Dr. Richard L. Day The selection of the group of subjects to be used in a test procedure is important. If conclusions pertinent to a large population of individuals are to be drawn from a small group of test subjects, it is vital that a representa- tive sample be available. If the test subjects are not representative, results are not indicative. In any experiment, a good approach is to divide first the questions to be answered and the criteria for measurements. The next step is to determine the known extraneous factors which may influence the results and to set up the experi- ments in such a manner that the effect of all complicating variables on the re- sults can be accounted for. "The essence of the (statistical) method lies in the determination that you are really comparing like with like and that you have not overlooked a relevant fact"(l)(one that is capable of producing bias in the re- sults)." The various statistical techniques that are available for the treatment of data can then be applied. It must be remembered that no statistical technique can uphold inadequate data. By proper statistical analysis it is possible to de- termine whether results obtained are within a normal range of variation or if the chance of obtaining such results is so small that it can be assumed to be a result of the factor that is being measured. TABLES "After a series of observations have been obtained, the first object; is to express them in a simple form which will permit directly or by means of further calculations, conclusions to be drawn. The worker must first consider the ques- tions which he believes the material is capable of answering and then determine the form of presentation which brings out the true answers most clearly." (l) Pearl suggests that in the construction of tables, the following questions be considered. "What is the purpose of the table? What is it supposed to accomplish in the mind of the reader? Wherein does its failure or attainment fall?" (g) GRAPHS "Graphs should always be regarded as subsidiary aids to the intelligence and not as the evidence of association and trends. That evidence must be largely drawn from the statistical tables themselves or in other words, graphs should not be substituted for statistical tables." REFERENCES (1) A. Bradford Hill. Principles of Medical Statistics. London, Lancet, Ltd. 2nd Ed. 1939. (2) Raymond Pearl. Medical Biometry and Statistics, Philadelphia and London. W. B. Sanders, Co. Ltd. 2nd Ed. 1930. 63

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Clothing Test Methods, Edited by L.H. Newburgh (Physiological Tests) and Milton Harris (Physical Tests) of Subcommittee on Clothing of the National Research Council (U.S.A.) Get This Book
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