HUMAN ENERGY COST OF fiLECTED FARMSTEAD TASKS Thesis for fit: Degree of M. S. MICHIGAN STATE UMVERSITY Robert Dean Fox 1958 THESIS ‘.|"‘II4"I|IIII I'll l'll n,|‘ll|.l HUMAN ENERGY COST OF SELECTED FARMSTEAD TASKS BY Robert Dean Fox A THESIS Submitted to the College of Agriculture Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Agricultural Engineering 1958 Approvei by flue/lag j W T a N’ 264' 5'? (g. 7&5? ACKNOW LEDGEMENTS The author expresses his sincere gratitude to Dr. Merle L.: Esmay of the Agricultural Engineering Department, for his guidance and many helpful suggestions during the course of this study. The author feels deeply indebted to Dr. A.W Farrall , Head of the Agricultural Engineering Department, for making possible the research assistantship for this study. The author is very grateful to the North Central Research Committee, NC 23, on farm buildings, who provided the Agri- cultural Engineering Department with the funds for this study. The author also wishes to thank the individuals who acted as subjects in executing the tests. They were: subject 1 — Ed Wilkie, subject 2 - Ed Fox, and subject 3 - Mel Gomulinski. TAB LE OF CONTENTS Page I.INTRODUCTK»J .............................. 1 11. REVIEW OF LITERATURE ............... .. . . . 4 A. Physiological Background . . . ,i ............. 4 B. Energy Studies .......................... 12 UL APPARATUS ............................... 14 A. Kofranyi Meter ......................... 14 B. Aliquot Bladders ........................ 20 C. Mouthpiece and Valve ................... 20 D. Nose Clamp ................ . ........... 21 E. Connecting Hose ........................ 21 F. Cflass Syringes ........... .............. 21 G. Beckman Oxygen Analyzer .. . . . . . . . . . . . . 23 INK PROCEDURE ..... ...H..H..”..H.. ...... 29 A. Silage Pitching Tests . .................. 30 B. Climbing Tests ................... . ..... 31 C. Treadmill Tests ...................... 32 D. Integral Tests ........................ . . 32 E. Steady State Tests ...................... 33 F. Handling of Gas Samples ................ 33 G. Oxygen Analysis ........................ 34 H. Processing of Data ..................... 34 V. RESULTS ............ . ....... ..............40 VI. VII. VIII. IX. XI. IA. Subjects ..... . .......................... 4:0 B. Basal Tests ............................ 40 C . Pitching Silage Tests . . . '. ............ . .. 43 D. Climbing Silo Tests .................... 49 E. Treadmill Tests ........................ 52 DISCUSSION . . . a ........................... 56 A. Subjects ............................... . 56 B. Basal Tests .. ........................... 56 C. Silage Tests ............................. 57 D. Costs of Pitching Silage ................. 57 E. Climbing Tests ........ . . . . . . ........... 59 F. Treadmill Tests ........................ 59 CONC LUSIONS ........... . ....... ' .......... 60 SUMMARY ...................... i ........... 61 SUGGESTIONS FOR FUTURE STUDIES ...... 63 REFERENCES ............................. 64 APPENDIXI ..... ..... ...... ...... .....67 Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 1 10 ll 12 l3 14 15 16 17 LIST OF FIGURES Oxygen intake-work relationship Oxygen requirement 8: intake during moderate exercise Oxygen requirement 8.: intake during severe exercise Recovery of pulse and oxygen intake rates Kofranyi meter Calibration curve for Kofranyi meter No. 1005 Expired air flow rate Front view of subject with Kofranyi meter in place Back view of subject with Kofranyi meter in place Sample collection and storage equipment Beckman gas circuit Oxygen analysis equipment Nomograph for determining factors to reduce saturated gas volumes to dry volumes at 0°C. and~ 760 mm. Hg. Nomograph for determining Calorie value per liter from oxygen content of expired air Nomograph for finding body surface area from height and weight Results of basal tests Results of the silage pitching tests Page 11 11 15 18 19 19 22 27 28 36 37 39 42 45 Figure Figure Figure Figure Figure 18 19 20 21 22 Effect of silo position and Speed of work on the energy used by subject 4 Effect of door height on the energy used by subject 4 while pitching silage Comparitiveenergy requirements for selected farm activites ' Results of climbing tests Results of the treadmill tests Page 47 48 50 53 55 Table Table Table Table LIST OF TABLES Results Results Results Results of the of the of the of the basal. tests silage pitching tests climbing tests treadmill tests Page 41 44 51 54 INTRODUCTION Mechanization of farmyard Operations has lagged far behind the use of machinery in field Operations. One reason for this lag is that no direct and convenient method of justifying the pur- chase of materials-handling equipment is being used. In the past the farm Operator's personal'Opinion of the convenience of the equipment and the time saved by using the equipment have been the usual basis for purchase. . There is a definite need for a method of objectively determining the practicability of using such equipment. The human energy cost of doing a job is a method of ob- jectively determining the need for mechanizing that job. Human energy requirements can be employed in selecting and designing the equipment best suited for a particular job. Energy exPendi- ture data can also be used in planning building layouts, work pro- cedures and techniques. This study was conducted to measure the amount of human energy required to hand pitch silage from an upright silo. This research problem was also designed as a pilot study to deveIOp techniques and procedures for further energy measurement studies to be conducted outside the laboratory. Oxygen _i_s_ a measure qf_energy The human body is much like an engine, it must use fuel to remain animate. The fuels utilized by the body are chemical compounds which are oxidized to give the body energy. They com- bine chemically with oxygen in the oxidation process. Therefore, the amount of energy used by the body can be determined by mea— " suring the oxygen consumed by the body. In this study the expired air was metered and its oxygen content measured to ascertain the oxygen used by the body. The body fuels depend on the diet of the person and other physiological factors, however for this study these elements were considered to vary an insignificant amount as compared to some other uncontrollable variables. Work energy In this study the work energy requirements were found by subtracting the energy required for standing at rest from the energy required to do the work. The position of standing at rest was cho- sen as a basal rate because it is the normal position for a farmer when working and it has been used as a basis for several other en— ergy studies of similar nature (6,27). Tests There are two types of oxygen collection procedures which are used to measure the oxygen consumed by the body while doing Wlork. The steady state method can be used for exercise that reaches a constant Oxygen consumption rate. The test is started after the Oxygen intake rate becomes stable and steps before the end of the exercise. The integral method collects Oxygen from before the exercise begins until the end of the recovery period. The latter type of test was used in this study because it can be used for tests of short duration, while the steady state test should have a pre -t.est exercise time of about ten minutes. The tests were run under actual field conditions. This was made possible by the use of the light weight Kofranyi meter for metering and sampling the expired air. These field tests are an effort to obtain data on the expenditure of energy while working under the exact conditions that a farmer would encounter. 4 REVIEW OF LITERATURE PhysiolOgical Background Oxygen re quire ments Morehouse and Miller (20) stated that the human body re- quires a continuous supply of oxygen to all tissues. Oxygen can not be stored in tissues so must be constantly supplied by the blood stream. The muscles require a greater amount. of Oxygen during exercise. The oxygen requirement of the body is determined largely by the characteristics of the exercise. Temperature and humidity also affect oxygen utilization. Gould and Dye (14) stated that the additional call for oxygen is satisfied by a larger flow of blood to the muscles. This can be accomplished by diverting blood to the contracting muscles from less active regions or by increasing the volume of blood output by the heart. He art output Heart output (20) is the product of two factors, stroke volume and heart rate. The increased blood flow during exercise is a - result of an increase in both factors, but the relative increase in each factor depends on the nature of the exercise and the physical condition of the subject. Indication of a subject's physical condition According to Riedman (26), a slow pulse rate in the standing and reclining positions, and a small difference between the two are a sign of excellent physical condition. Normal pulse rate reclining is four to five beats per minute lower than when sitting; sitting is six to eight beats per minute lower than standing. A person in good physical c0ndition will have a rise of less than ten beats per minute whereas a weak subject will show an increase of twenty to forty beats per minute when moving from the reclining to the stand- ing position. Factors affecting heart output Accurate data (20) on the cardiac output in various types and intensities of exercise are not available. A great deal is known about the changes in heart rate which accompany exercise but little is known about the equally important adjustments in stroke volume. The stroke volume (20) is affected by inadequate venous re- turn. During light’muscular work or rhythemic contractions such as running, the blood flow in the veins is stimulated by the moving muscles, however in heavy static work, such as weight lifting, the contractions of the muscles may hinder the venous return of blood to the heart. Morehouse and Miller (20) related that several factors affect heart output. Some of them are: 1. The cardiac output is usually reduced when the subject stands; since pulse rate increases, that indicates a reduction in stroke volume. 2. The output of the heart is increased temporarily by eating. 3. Exposure to cold slows the heart rate but increases stroke volume, leaving cardiac output unchanged unless shivering occurs, which increases cardiac output. 4. Exposure to warmth increases resting output; the heart rate is increased with a slight reduction in stroke volume. 5. Emotion increases the‘heart rate at rest and during light exercise, but probably has little influence on the maximal heart rate. 6. The same is probably true, to a lessor degree, of an in— crease in environmental temperature and humidity. 7. Adverse conditions such as fatigue, lack of sleep, malnu— trition and acute infections may reduce the maximal cardiac output capabilities of an individual. 8. Heart rate varies with age; decreasing from birth to middle age and increasing slightly in older peOple. Heart rate The use of heart rate as a measure of energy expenditure is a much debated subject. As can be seen from the above list, there are several variables which affect heart rate besides muscular activity. Most of the variables can be controlled by a suitable arrangement of tests and by choice of subjects. Henderson and Haggard (15) stated that for light activities such as a walk at an easy pace, the chief compensation for the in- crease in blood flow is an increase in pulse rate. ' Beyond moder— ate exercise the stroke volume and oxygen utilization are involved along with a further increase. in heart rate. Gould and Dye (14) observed the stroke volume of non-athletic individuals to be nearly prOportional to the blood flow during rest and exercise. However, in athletes, the stroke volume generally increased considerably, in some cases forty to fifty percent during exercise. Ford and Hellerstein (12) in studies of industrial workers found poor correlation between heart rate changes and energy expenditure . Morris (23) stated, "Heart rate is not satisfactory for esti— mating the physiological cost of work." Karpovich (17) published a graph which showed the heart rate- work load relationship for four men while riding a bicycle ergometer with varying loads. These subjects had nearly linear relationships between pulse rate and work load up to a limiting load; 4,000 foot— pounds in one case and 8.000 foot-pounds in the other three cases. This curve was used as a basis for tests at North Carolina by Suggs and Splinter. They (29) used a strain gage fastened to the temple for measuring the pulse rate of the subjects and then con- verted to energy consumed by means of Karpovich's curve. Oxygen intake The oxygen intake for a worker at various levels of work has been shown (17) to be a direct relationship. Figure 1 shows the relationship between the oxygen intake and work on a bicycle ergo- ,w 0 N O Oxygen Intake in Liters/Min. 8 2000 4,000 6,000 8000 l0,000 Work in Foot-Pounds Figure I. Oxygen Intake-Work Relationship. From Reference I7.. 6.0 I g Steady State --- Oxygen Requirement -‘ 40 e 5 \\ ' Oxygen intake ‘ ”WOO“ " \ O 3‘20 Debt / ' Repaid Oxygen Debt _ //,- 2 46 8 l0i2 l4i6l8 Time in Minutes Figure 2. Oxygen Requirement 3 intake During Moderate Exercise. Ftom Reference I3. meter. Karpovich (17) has found that the oxygen intake rate does not parallel the Oxygen usage rate in the body. When muscular activ- ity begins, there is not enough oxygen at the muscles, so anaero- bic sources of energy are used to supplement aerobic sources which use the available oxygen. Those stores of anaerobic energy are limited and the body produces more energy by increasing the oxidation rate whenever possible. The anaerobic energy is mea- sured by the oxygen that must be taken in to replace it. This de- lay in the supply of oxygen to convert fuels into energy is called oxygen debt. Steady state exe rcise Figure 2 (18) shows the time—oxygen relationship for moderate exercise. The oxygen requirement rises from the base level to the work level the instant work starts. The oxygen intake requires from two to five minutes to reach the usage level. The period where oxygen intake is equal to oxygen used is called the steady state work level. There is a recovery period after the stOpping of exercise when the oxygen debt is repaid. The length of the recovery period is dependent upon the intensity of exercise. Severe exercise There is a limit (14) to the amount of oxygen that can be Supplied to the muscles. The limiting factor in the body is the 10 ability of the blood stream to carry the oxygen. Therefore, if the_ intensity of exercise is too great, a steady state condition will never be reached and the oxygen debt will continue to increase un- til the muscles become exhausted. Figure 3 (13) is an example of this type of exercise. Recove ry period After the stepping of exercise (17), the oxygen intake rate declines until the pre-exercise rate is reached. This fall in oxy- gen intake rate can not be measured easily, however, it has been found (18) that heart rate returns to normal much lewer than oxygen intake rate (see figure 4). Thus heart rate can be used to estimate oxygen intake rate, for when heart rate returns to normal it is certain that Oxygen intake rate will be back to normal. 11 I4 - w ———- Oxygen Requirement I '2 ' lbw} ——- Oxygen intake '0 ' 9 Doing: ‘ s e - , .1 6 P ’ .5 5 4 - IRepaid g. 2 - :Oxygen Deb o ........ 4424/ 2 6 l0 I4 18 . 22 Time in Minutes Figure 3. Oxygen Requirement e intake During Severe Exercise. From Reference I3. Puiee Rate 0 4O 80 iZO l60 Time in Seconds Figure 4._Recovery at Pulse and Oxygen-Intake Rates. From Reference I8. 12 Ene rgy Studie 5 Use in design Dupuis (11) found from energy measurement tests that the energy used in driving tractors could be reduced as much as 28.5% by alterations on a commercial design. He accomplished this by changing the location of the brake and clutch petals, reduc— ing the Operating force needed for these pedals, using a prOperly designed seat, moving hand Operated levers within easy reach, and shortening the Operating stroke of the levers. Morris (21), in tests at Cornell, found that the time required to milk cows was equal for all milking platform heights. The en- ergy used by the Operator while milking a cow on the higher plat- forms was significantly less than the lower ones. The highest platform tested was 36 inches and it was the most efficient in en- ergy consumption. This points out the value of energy measure- ment in addition to time studies as a tool in the evaluation of a work system. Ross (27) used energy in analyzing the entire materials hand- ling system of a farm. He divided the farmer's movements into short elements of constant energy consumption rate; then using en- ergy rates from previous studies, the total energy used in each element was computed. The total energy used in any system was determined by summing the energy used by each of the elements in that system. 13 Energy studies can be used to select the best Operating speeds. Suggs and Splinter (29) found that as machine Speed increased, en— ergy efficiency usually increased to a maximum and then declined. Their tobacco priming studies were conducted on subjects while walking and while riding on a low seat at three Speeds. The great- est number of leaves were picked at the high Speed but the great- est number of leaves per unit of work were picked at the inter- mediate Speed. The results were: machine methods were three to four times as fast as hand methods, however, the Optimum machine Speed was fifteen times as efficient in energy consumption. Because driving a tractor is a sitting Operation, many peOple tend to think it is easy work. Physiological tests (11) have shown that manure loading with a tractor takes as much energy as cutting logs or carrying sacks of flour; near the limit of continuous human performance. A study (23) of the daily activities of a group of farmers has shown energy expenditure to be twenty to thirty percent higher than was found for a grOUp of industrial workers. 14 A PPA RA TUS Kofranyi Mete r Description The Kofranyi meter is 10.1 inches high, 8 inches wide and 4.4 inches deep, (see figure 5). It, with the accessory collection equipment, weighs approximately 8 pounds. The meter is used to measure the volume of eXpired air and to take a sample of that air to be analyzed for oxygen percentage. The Kofranyi is a dry gas meter with several compartments which fill alternately. The gas flowing through the meter drives a series of gears which turn the recording dial. The gas flow also drives a small aliquoting pump which draws a sample of air from that passing through the meter and pumps it into an aliquot bladder. There is a thermo- meter in the meter box to measure the air temperature as it passes through the meter. Calibration The Kofranyi meter was calibrated to check the accuracy of the gas flow meter. Several Kofranyi meters had been calibrated at Michigan State University (19) and the method used in this study was similiar to their procedures. The air was evacuated from a Douglas bag, then air was pumped into the bag through a Precision— Wet-Test meter, and the volume pumped into the bag was recorded. The Douglas bag was always filled at a slow flow rate within the calibrated range of the Wet-Test meter. The air was pumped at uuuoz Scmnmom Um-.. .. . .Exmir. _ ..z .LJ. For .3. . m oudmwh 16 various flow rates from the Douglas bag through the Kofranyi meter, and the volume recorded. The actual flow rate was plotted against the Kofranyi recorded flow rate. This graph is shown as figure 6. The steady rate air flow through the meter during calibration is not a duplication of actual test conditions. A person wearing the meter is spending about half the time inhaling and half the time exhaling, therefore, an average flow rate of fifteen liters per min— ute from a worker would mean about thirty liters per minute for half the time and none for the remainder. Figure 7 is a graphical representation of this conception. The thermometer used in the meter was checked against a known accurate thermometer and was found to be accurate. Use The meter is very simple to Operate and requires very little instruction before it can be worn. It is strapped to the back like a rucksack as shown in figures 8 and 9. Tests (16) have shown the energy cost of wearing the meter to be negligible. There are two aliquot sample sizes which can be used, approx- imately 0.6% or 0.3% of the total air flow. When the aliquot sample size was 0.6% and the bladder became full, the meter read a lower volume than actual. The 0.3% sample size was used for all the tests in this study, because there seemed to be less back pressure against the expiring of air. The meter was oiled once a week to insure a minimum of 17 0007.2... .02 .202 35:3. .8 2:50 5:39:50 .0 050$. 00 2352 can. «3:... c. On 0? On 25 32... .384 ON 0. 0. ON on Cd On 00 ’UIW/SJGii‘I U! emu Mold ”910908 M00110» 18 O ‘5 .5 220 3 F1 F—l f“? 0.. a l5 3 A 3 .. ..-.__ --.__. _.__.__V_°'_°.92_ j '0 l Flow Rate 3 5 O 0: l 3 0 J L4 . L; 2 u. 0 2 4 6 8 Time in Seconds Figure 7. Expired Air Flow Rate l9 Figure 8. Front view of subject with Kofranyi meter in place Figure 9. Back view of subject with Kofranyi meter in place 20 driving force. In cold weather the meter tended to run harder, requiring more effort for breathing. The meter collected moisture which had to be poured out of the inlet tube periodically. Aliquot Bladders The bladders used were of two Sizes, 100 milliliters and 1,000 milliliters. They were constructed of rubber with grooves along the sides to reduce their tendency to Spring to a shape when - evacuated. There was a Slight aSpirating of air by the bladders when they were at low pressure. The volume of'the sample about to be taken should always be checked before the test is started, to insure adequate bladder size for the sample. If the bladder becomes full, its back pres- sure will get as large as that produced by the aliquot pump and no sample will be taken. The bladders were stored full of expired air when not in use to keep the walls saturated with carbon—dioxide, as carbon—dioxide has a very high diffusion rate through rubber. Mouthpiece and Valve The rubber mouthpiece fits into the mouth and has small flanges which can be bitten to secure the mouthpiece and valve (see figure 8). The. plastic valve fastens to the mouthpiece. (It has two mica discs with backup Springs which permit the passage of air in one direction only. The air comes in from the outside and is expired through the tube to the meter when the wearer is breathing. It has a dead Space of 32—41 ml. and is very light in 21 weight, no support besides the mouthpiece is necessary. Nose Clamp The nose clamp used was a common swimming nose clamp. Connecting Hose The hose connecting the plastic valve to the meter was made of flexible rubber about one inch inside diameter. A clamp was placed on the right support strap of the meter to hold the hose in place during active exercise. The hose should be stored in a warm place to remove some of the moisture that condenses in it. The corrigations in the hose do not permit the moisture to be poured out. Glass Syringes The glass syringes used were thirty and fifty milliliters in capacity. They were used to store and transfer the expired air samples from the time of collection till they were analyzed. Tests (16) have shown that samples could be stored in glass syringes for up to 72 hours without affecting the composition of the sample. The syringes were kept well sealed with stOpcock grease. The best criterion for a good seal is that a portion of the plunger in contact with the cylinder be tranSparent in appearance. A frosted appearance indicates a poor seal. The rubber tubing on the outlet end of the syringe was clamped with a screw clamp. A picture of the sample collection and stor- age equipment is shown in figure 10. 22 «confidence Omaha: can noflpomuuoo 035nm .3 onswfih .... \x.>fll‘.t. .Ks. .sfirflrf‘vr. $49.”) JUL; ._...\.N..n f..........v......:. fire; :.%r‘..flwl.\vw’ . r .40. .. .. 1-... 23 Beckman Oxygen Analyzer Principle 2f Operation The model E2 Beckman oxygen analyzer is an instrument used to measure the Oxygen percentage in a sample of gas. The E2 model has two ranges which can be used; one can measure oxygen percentages between zero and twenty-five, the other between six- teen and twenty-one. The Beckman measures the magnetic susceptibility of a gas with a magnetic torsion balance. Oxygen is one of the very few gases which are strongly paramagnetic, therefore the amount of oxygen present in a sample of gas can be easily measured. The magnetic balance consists of a mirror attached to a dumbbell-shaped test body which is supported by a quartz fiber. The test body is subjected to a magnetic rotational force which is dependent upon the difference between the volume sus- ceptibilities of the test body and the gas which the test body“ diSplaces and upon the physical constants of the instrument. Whenever the susceptibility of the gas changes, as a result of changing composition or pressure, the test body rotates. The test body is returned electrostatically to a null position by manually varying the voltage between the test body and the two reference vanes. The oxygen concentration in the analysis cell is read from'the.position of the potentiometer dial (called a Helipot Duodial) used to vary the voltage. A linear rela- tionship exists between this voltage and the oxygen concentr- ation. The test body is at its null position when the narrow light beam reflected from the mirror is centered on the ver- tical engraved line in the translucent scale. (3) Calibration There are two electrical adjustments necessary on the Beckman, the ZERO and the SPAN. The ZERO adjustment fixes the zero point of the linear scale and compensates for differences in the 24 magnetic susceptibility of the background gases and for changes in the reSponse characteristics of the analyzer. The ZERO calibra- tion was accomplished by setting the Helipot Duodial on zero, set- ting the range selector on the 0 to 25% scale and turning the ZERO knob until the light beam is centered on the vertical black line when carbon—diOXide is placed in the analyzer. A correction for the background gases was necessary because carbon-dioxide was used to calibrate instead of nitrogen. The correction factor was computed using the information in the manual (3) , as follows: The equivalent oxygen percent in the background gases is equal to the fraction of the sample which is C02 times the equi— valent oxygen % of C02, plus the fraction of the sample which is N2 times the equivalent oxygen % of N2. Assuming a R.Q. of 0.85 and an 02% of 15%, we see; For co2 . -2776 x .626 : .08% For N2, .7224 x .385 = .267. Total .3471. Equivalent oxygen percent in calibrated gas, C02: .85 x .626 Z .533% The difference in equivalent oxygen percents is equal to -.19%. The correction is negative since the background gases are less diamagnetic than the calibrated gas. All the gas samples analyzed in this study were near enough to 15% that the correction factor 25 of -0.l9% can be applied to all analyzer readings to correct for background gases. The SPAN adjustment was made using outside air as the reference gas. The Helipot dial was set at 20.93% oxygen and the light beam centered with the SPAN knob. There was an additional correction made to the oxygen per— centages read on the Beckman. This was necessary because the gas samples and the outside air were not dry when they were an- alyzed. This correction factor was found by subtracting the water vapor correction factor due to the water in the calibration outside air from the water vapor correction factor due to the expired samples. The correction factors for each of the elements was found from the formula, Pt given in the analyzer manual Pt - PHZO (3). Pt is the total gas sample pressure in the analysis cell measured at the outlet nipple. PHZO is the partial pressure of water vapor in the gas sample measured in mm. of mercury. This factor varied with the barometric pressure and with gas pres- sure, therefore, it was computed for each sample. Use The Beckman is a very simple instrument to use, however a few precautions were taken to insure prOper Operation. a. The ZERO point was calibrated every week. b. The SPAN was calibrated each time the analyzer was used. 26 c. The analyzer was allowed to warm up at least one-half hour before samples were analyzed. d. A Sorensen & Co., Inc. model 5005 a.c. voltage regu— lator was used to insure a steady voltage supply. e. The vacuum pump oil level was checked occasionally. f. The stopcocks and hose system was checked for air leaks. g. The light beam source lamp has an expected life of ap- proximately 15 hours, therefore it should be on only when readings are being made. The gas flow circuit is shown in figure 11 and a picture of the oxygen analysis equipment is shown in figure 12. 27 .328 «no 5.5.25 Ell—D...— 32:23 : 02.5 :aExoom 9:20 380w - .3216. 3.3235 >2..- 09...: .: 23E — co Sim 2955 3:... 38:35 95:. .52.) _ H— A .088 28 udofimgv o 39:98 Gumcflxo :2 63m:— 29 PROCEDURE The two types Of oxygen collection methods are the steady state and integral. The steady state method has several advan- tages over the integral method. It is used when the oxygen intake rate is constant, therefore, any aSpirating of air by the sample bladder when it is at low pressure will have no affect on the test. Also any stagnate air that might be in the valve, rubber tube Or Kofranyi ~meter will probably be of the same oxygen content as that which is being expired during the test. The integral method is based on the assumption that the repayment of the oxygen debt, by the body is entirely efficient. The integral method has the advan- tage that it can be used on tests of short duration and tests where a steady state level of oxygen consumption is not reached. The tests used in this study were all of the integral type, however, the procedure for steady state tests is given also. The procedures given here are similar to those used by Insull (16) in tests at the Army Nutrition Laboratory. The subjects were oriented to the equipment before any tests were administered. The tests were conducted at least two hours after the Subject had eaten. Fifteen to twenty minutes were al- lowed before a test. to permit the subject to reach the basal energy consumption level. A standing basal was run before each working test. The basals were conducted as a six minute integral test with the sub— 30 ject standing in position to begin work; the same position he would be in during recovery. All the basals were made standing on the ground except those for the climbing tests, which were made while the subject was standing on the steps in the silo chute. Standing in the chute required more Calories per minute than standing on the ground, which points out the importance of taking a basal test in exactly the same position as is used in the recovery period. The data sheet used for the tests is shown in Appendix I. Silage pitching tests There were four subjects used in the silage pitching tests. Three tests were conducted with subject 1, four tests with subject 2, five tests with subject. 3, and thirteen tests with subject 4. The largest number of tests were carried out on subject 4 to col- lect enough data to analyze the affect of some of the variables on the amount of energy used in removing silage from a silo. The tests were executed in a fourteen foot diameter silo located on the Michigan State University farm. This limited the tests to one each day. All subjects were familiar with the procedure used in re- moving silage from a silo. The corn silage was removed in layers of between three and four inches each. Each layer was started at the door and continued across the silo. There was approximately 120 forksful of silage in each layer. The subjects were instructed to work at their normal Speed: 31 the work rates varied from‘5.2 forks per minute to 9.3 forks per minute. They were also told to try pitching full forksful during the test. The silage was weighed for several tests and the weight per forkful computed. It was found that. the weight. per forkful could be estimated quite accurately. Thus the amount of silage removed was estimated for most tests,with spot weighing checks. The height the silage had to be pitched varied from zero to twenty-four inches. The fork used in the test was fifteen inches wide and had ten tines 16.5 inches long. The recovery period after the tests was carried on until the subject's pulse rate returned to the pre-work level. Climbing tests Two subjects were used for the climbing tests. Subject 2 enacted four climbing up and down tests and two climbing up tests. Subject 4 carried out five climbing up and down tests, seven climb- ing down tests and sixteen climbing up tests. Subject 4 was the only subject who executed enough chute basals to obtain an average of this type of test. The tests were conducted at speeds varing from 28 feet per minute to 60 feet per minute. The silo used for the climbing tests had steps of two sizes. The subject climbed each size step alternately, placing both feet on each step. The size of one step 32 was 9.5 inches and the other was 18.5 inches high. The subjects climbed to a height of 28.5 feet. during each test. The climbing up tests. and the climbing down tests were carried out for a total test time of six minutes. The climbing up and down tests were administered for a total time of nine minutes. Treadmill tests Subject 2 executed 4 tests, subject 3 did 3 tests, and subject 4 ran 8 treadmill tests. The treadmill tests were made at 2.54 feet per minute (1.75 mph). The subject walked for two minutes; the total length of the oxygen collection period was six minutes. Integral tests l. The Kofranyi meter was strapped in place. 2. The connecting hose was fastened to the meter and to the plastic valve. 3. The mouthpiece was placed in the mouth and the plastic valve checked to insure pr0per Operation. 4. The nose clamp was put in place and checked for air leaks. 5. The aliquot bladder was evacuated orally, clamped and put in place. 6. The subject stood at rest, breathing through the meter, ready to begin work, for five minutes (see figures 8 and 9). 7. The initial volume and temperature were read. 8. The clamp on the aliquot bladder was removed, the me— tering lever was turned, and the stOpwatch was started. 33 9. The subject started. work, worked a predetermined amount, stOpped and the time when work stOpped was recorded. 10. The subject stood at rest until he returned to normal standing energy consumption rate. This was determined by check- ing the pulse rate until it returned to pre-work rate. The meter was stOpped and the aliquot bladder was clamped. 11. The final temperature and volume were read. 12. The aliquot bladder was sampled. Steady state te sts l. The collection meter was placed on the subject and check- ed as in steps one through five above. 2. The subject began work and continued until he reached the steady state energy usage level. 3. The initial volume and temperature were read. 4. The clamp on the aliquot bladder was removed, the me- tering lever was turned, and the stOpwatch was started. 5. The subject resumed working and worked a predetermined amount, then stOpped. 6. The time was noted, the meter stOpped and the aliquot bladder clamped. 7. The final temperature and volume were read. 8. The aliquot bladder was sampled. Handling of gas samples 1. The aliquot bladder was removed from the Kofranyi meter, 34 checked to see that it was not excessively full, and kneaded well. 2. The bladder was connected to a three-way stOpcock along with a glass syringe.(See figure 10). 3. The connecting. hoses were evacuated orally. 4. The syringe was flushed three times with expired air samples of from five to ten milliliters each. 5. A twenty-five to thirty milliliter sample was drawn into the syringe, and the connecting hose clamped with a screw clamp. 6. Two syringes were taken from each sample bladder, pro- viding the sample was large enough. Oxygen analysis l. The power was turned on and the Beckman was allowed to warm up for thirty minutes. 2. The Span setting of the analyzer was checked. 3. The system of connecting tubing was evacuated. 4. The system was purged with the gas sample to be analyzed. 5. The pilot light was turned on and the Helipot Duodial was turned until the light was centered on the vertical black line. 6. The reading on the Duodial was taken and the oxygen per- centage of the sample computed. 7. A second sample was analyzed for each syringe. Proces sing of data 1. Information needed a. Volume of gas eXpired 35 l) Kofranyi correction factor b. Temperature of expired gas c. Barometric pressure d. Oxygen percentage of eXpired gas e. Outside air temperature, dry bulb f. Outside air temperature, wet bulb 2. Method of processing a. The recorded volume was corrected for the meter factor; this factor was taken from figure 6, with the Kofranyi flow rate taken as two times the average flow rate for the entire work time. This was to allow for inspiration time while breathing. b. The expired air was assumed to be saturated with water vapor. The volume was corrected to dry air at standard temper— ature and pressure, using the nomOgraph in figure 13 to obtain the correction factor. c. The Oxygen percentage was corrected for background gases by reducing the indicated percentage by —0.l9%. d. The oxygen percentage was corrected for moisture con- tent of the gas sample by the factor obtained using the formula on page 25. The correction factor for the outside air was subtracted from the one for the expired air sample. e. The calories per liter of expired dry air were deter- mined from Weir's nomOgraph (30). The nomOgraph is shown in figure 14. 36 44 AT 1 S 42 ..§. 8 I ’9 DRY VOLUME IN MM. OF H6. 0 0 91“].““ 0. AND 760 MM. H6. 90 0| 1‘111'91‘1'1‘1‘1 O. W BAROMETRIO PRESSURE 75 TEMPERATURE Gt 0 figure i3. Nomograph For Determining Factors To Reduce Saturated Gas Volumes To Dry Volumes At 0°C. And 760mm. Hg. From Reference 7. on no cccocom ES... :2 togaxw co 23:00 .5ng Each. .3...— SE «26> 0.330 955.522” .3 £20232 .3 £53“. 3:... can. 33> 2.3.60 2.0 2.0 9.0 2.0 0N0 .N.0 NN.0 MNO ¢N0 nNd 0N0 5N0 b _ _ __ _ b _ .— a_._pfi...r_u__e___.___.___._.Lfl_u.__ MN. 0.2 mm. . 0.0. 0.0. :4 .3396 E .8235 cc cog—39.: 38 f. The calories per liter of expired dry air were multiplied by the corrected volume of eXpired gas to obtain total calories for . the work done. g. The calories required for the basal standing test were then multiplied by the necessary factor to give total basal calories for the same length of time as the working test. h. The basal standing calories were subtracted from the total calories to give work calories for that test. i. The subjects were compared by dividing the work calories for doing a task by their body's surface area. The surface area of the body was found by using the subject's height and weight and the nomOgraph shown in figure 15. 39 M2: w°"25x H” x 7|.84 ieo 4’3 p— ‘-—6r-'r 22 180-: .-9 2. Iro~- -6 0.8 ‘r- «r- ~-—5FT .5 i- L4 01.. (I) —9 5 - 3 B '2 mo-i- 5 3 g; r—6 z 2 4 U '— m - 2 § 3 l30-4L.3 - < z "0 I- .- z ' l; < . g -L m g o. z —-4F1‘." < _ Z - I20 - - 3 0.8 .— 1: I E fl 2 ‘9 ‘9 S g . 2:3 «3 0.7 Ho—_ ‘6 0.6 fir- loo-J Figure l5. Height And Weight. From Reference 7. Nomograph For Finding Body Surface Area From W EIGHT m POUNDS 2 20 200 ISO 160 MO l20 100-: 1 [III IIIITIIIIIIHIIIHHII" 00 O 8 .p 0 I ‘ I I 'L 0 3 IN KILOGRAMS WEIGHT zo-J 40 RESULTS Subjects Subject 1 is approximately 66 inches tall and weighs 155 pounds. From figure 15, his body surface area was found to be 1.8 square meters. He is experienced in doing farm chores. Subject 2 is approximately 67 inches tall and weighs 160 pounds. His body surface area is 1.84 square meters. He has spent all his life on a farm. Subject 3 is 75 inches tall and weighs 215 pounds. His body surface area is 2.29 square meters. He is not from a farm, but. he has had limited farm experience. Subject 4 is 67 inches tall and weighs 165 pounds. His body surface area is 1.88 square meters. He is experienced in farm chore Operations. Basal tests ’ The results of the basal tests are shown in Table l. The results are given with the standard error of the means for both the test results and for the results corrected for the size of sub- ject. Figure 16 shows in bar graph form, the comparison of the subject's basal tests. Statistically, there is significant difference in the corrected basals between only subject 3 and the other subjects. The t-test was used to compare the subjects. The comparisons are: tl,2 3 .56 111,4 3 .059 41 mm.o.o Gate 65 00 no.7; phobcgm oomoé 023.0 «.mmod mowed smog may .«0 houno Uhmvcmpm hmoé om; NH NE-G....E\_MU .EE\HMU a. 5 wow: >whecm new: uwnecm mvmmh .«o HHDZU 013m ESP 7: OZHQZmU .CME\.MD a. N 5 wow: twmumcm vows >whecm munch. mo QZDOmO MIR. ZO OZHQZAVAHW mhmm—H dwhccm mBmmH OZHIUHHQ @0370. were... mmwhm>< mono.o m. :25 m m8... v coed m .n.\.mo 5 wow: >mxecm Path. mo .02 HIP .mO mHJDmmm .N HAm3 . . . . - u q d m. . m. d D 1N m... o m. an I. u v m o -o w. W , 10 P o , m x Ia x o x .. s Q. .83.. I a i o n\. 0.2:: i0 3.3.52.8 3.05 c. in 32...... 98. .o 3. «film. an. a no. 48 82...... 9.22... 2...; e .335 an no»: 3.20 2: :o 20.2. .03 00 625 «2.2.. c. 20.2 .000 ew mm Cu m. m. S N. o. m m e .m. 2.6.... - . d _ - 1 u — _ - _ s. p. 0 Q o m 10d 10:) a! pesn Karena 49 been classified (22) as shown in figure 20. Three hundred and eight Calories per square meter—hour falls in the range listed as heavy work. The heavy work range is described as being tolerable for one hour. Morris (23) lists the energy requirements of shoveling grain. Using a twenty pound load, with ten shovels per minute, he re- lated that the energy cost" of shoveling the grain six feet horizon- tally would be 7.2 Calories per minute. The average amount of energy used to pitch silage from the silo in this study was 5.] Calories per square meter-minute. For an average sized person, with a body surface area of two square meters, the energy c0nsumption rate would be 10.2 Calories per minute. This compares quite closely with the data given by Morris, for pitching silage would require more effort in loading the fork than pitching grain. The silage also had to be pitched to an exact location which would tend to raise the energy usage rate. Climbing silo tests Table three is the results of the climbing tests. Comparing the subjects; t Z 1.30 for the up and down tests and t = 1.16 for the climbing up tests. This is not a significant difference between subjects. When the energy used by subject 4 during the climbing up the silo tests was added to the energy consumed during the climbing down the silo tests, the total was greater than the energy used in .Nuuom ES... 50:52: Econ 93023 .8 3552300: 335 3:22.800 .0“ 23E 0%.» 00¢ 5.1.1.3440 z. >._._mzm.=: v5.03 Won _ L CON _ 00. O L _ p . i §§§§ Ammo; wzcmizxm 50 #58 zmo>x0 momdq no hzwzoqm>wo x103 >>ou4 2:232 ill >._._>_h0< PIG...— AQNB .2. a. O». N: 302m 2. @2335.) .836 soniaznn ..mm._ 3. 925.50 9.3 2..ng 62.0230 53% 0003 02.3dm ozju>ozm in! QM :84 n! @5550 96.. .1229». 02.55, azamhzmamco 225.3 was: «<0 < 92.28 925245 02.5.5.5 51 TABLE 3. RESULTS OF THE CLIMBING TESTS Climbing up tests Subject No. of tests Energy used Standard error in Cal/ft-mZ of the mean 2 2 0.218 0.0065 4 16 0.201 0.0082 Climbing down tests Subject No. of tests Energy used Standard error in Cal/ft--m2 of the mean 4 7 0.0758 0.0046 Climbing up and down tests Subject No. of tests Energy used Standard error in Cal/ft--m2 of the mean 2 4 0.248 0.0090 4 5 0.232 0.0085 52 the climbing up and down tests (see figure 21). There was no correlation between the speed of climb and the total amount of energy required by subject 4 while climbing the silo. Climbing up the silo used energy at the rate of 450 Calories per square meter-hour. Treadmill tests Table 4 and figure 22 show the results of the treadmill tests. The subjects compared as follows: t2,3 1 .48 t2"; = 1.79 t3’4 3 2.81 Anything above 2.26 is significant to the .05 level. Therefore, subjects 3 and 4 are significantly different in energy consumption. There was, however, less difference between subject 3 and the other subjects in this test than in any of the tests conducted. Climbin ng up fmh //////////////’ ////////////2~ Cli mbin no down Climbing up and down Climbing down . \\¢ I 1 ID 0 m o It) 8 N N. "'- a 0. o' o O O o inn-1; Jed 10:) ul pesn (Nana Subject Figure 2|. Results of Climbin q Tests 54 Nomod :umoé vmmo.o smog .05 mo House panacea oo .2 we . N 82.3.... mad mu; m w. 84 . $.N m m mo; ow; .v N ...E-EE\~MU .EE\~mU cw a: mum: >mhmcm poms >mnmcm~ Ewen. mo .02 wommnsm mBmHB AJH§Q