Work physiology is the study of physiological parameters of the body during work. Two of these physiological parameters are commonly measured to assess the cost of work : oxygen consumption and heart rate. In 1979 a theoretical model was developed to estimate some ergonomic parameters from age, height and weight. While this model predicted anthropometric, biomechanical and work physiology parameters, the present research was concerned only with the section of the model predicting work physiology parameters of oxygen consumption and heart rate from age and weight. In this study oxygen consumption and heart rate values were obtained from measurement of seven subjects working on an ergometer. These values were then used to test three of the equations in the predictive model. Two of the equations were found to be unreliable as predictors of oxygen consumption and heart rate for this sample, while one of the equations was found to be reliable. Further research with a larger sample is necessary before any firm conclusions about this section of the model may be made

Jeffrey, Glyn

Massey Research Online

Copyright is owned by the Author of the thesis.  Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only.  The thesis may not be reproduced elsewhere without the permission of the Author.  AN INVESTIGATION OF THE VALIDITY OF A SECTION OF A THEORETICAL MODEL TO PREDICT WORK PHYSIOLOGY PARAMETERS FROM AGE AND WEIGHT A RESEARCH REPORT PRESENTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF BUSINESS STUDIES AT MASSEY UNIVERSITY GLYN JEFFREY 1984 ii ABSTRACT Work physiology is the study of physiological parameters of the body during work. Two of these physiological pnram0tcrs are commonly m~asurcd to c:isscs!:; the cost o( work : oxy<._Jcn consumption and heart rate. In 1979 a theoretical model was developed to estimate some ergonomic parameters from age , height and weight . While this model predicted anthropometric , biomechanical and work physiology parameters , the present research was concerned only with the section of the model predicting work physiology parameters of oxygen consumpt i on and heart rate from age and weight . In this study oxygen consumption and heart rate values were obtained from measurement of seven subjects working on an ergometcr. These values were then used to test three of the equations in the predictive model. Two of the e quations were found to be unreliable as predictors of oxygen consumption and heart rate for this sample , while one of the equations was found to be reliable . Further research with a larger sample is necessary before any firm conclusions about this section of the mode l may be made. Abstract List or 1'c1blcs List of Figures Acknowledgement s 1 • Introduction iii TABLE OF CONTENTS 2 . The Cost of Work and its Estimation 3 . Description of the Experiment 4 . Results 5 . Conclusions 6 • References Page Number l. 1. iv V vi 9 28 40 64 68 7. Appendix I . Computation of regression of 72 IIR against Voi., for each subject 3 : 1 3 : 2 ) : J 3 : 4 4 : 1 iv LIST OF TABLES Mea n values for maximal o x ygen upta ke attained in various types of e x e rcise . Expc rimcnta] subjects /\g() .:i nd Woi.g h t . Vo'l. 111<1x i.lnc..l IIH max valu<..!~ ca l cu l c1tecd I rom equations by Dehn and Bruce , Bar-Or and Buskirk , a nd Astra nd a nd Rodahl. Pred i cted Vo2 max from the De hn and Bruce e quati on and Astrand ' s standardised data. Oxygen consumption and h eart rate values of seven subjects over the experimenta l trials . 4: 2 Values for compariso n of predicted Vo2 ma x from Equation I and Astrand ' s standardised data. 4: 3 Summary table of tests of predictive value of Equation I for s eve n subjects . 4:4 Actual values of Vo2 (x) and x . 4:5 HR max va lues calculated from Equation III a nd Astrand and Rodah l. 4 : 6 Pre dicted heart rates from Equation III using values of Vc2 = 0 . 35 Vo2 max. 4: 7 Prccicted heart rates from Astrand ' s formula using va l ues of Vo2 =0 . 35 Vo2 max . 4:8 Table showing heart rate values for Equation III with Vo2 = 0.35 Vo2 max d e rive d from Equation I and Astrand . 4 : 9 Predicted HR from Equation III with Vo2 = 0 . 35 Vo2 max derived from HR max . 4:10 HR from Equation III with Vo 2 = 0.35 Vo2 max obtaine d from Equation I , Astrand and actual HR. Page Numbe r 29 ~ 1 35 4 0 43 47 4 8 50 53 5 4 55 59 60 V LIST OF FIGURES 2 : 1 Oxygun con s umption during work . Photograph 1. Photograph 2. Photograph 3 . Photograph 4. 4: 1 Th e Repco Cycl e Ergome t er . Ergometer and apparatus for collection of expired air. Apparatus for collection of expired air and substitute Douglas Bag. Subj e ct about to insert mouthpiece for collection of expi red air . Scatte r diagram showing HR (beats min -1) against o2 consumption (L min -1) Page Number 10 3 7 38 38 4 1 57 vi ACKNOWLE DGEME NTS I wish to thank : Dr Antonios Vitalis , Business Studies Faculty , Massey University , Supervisor ; Dr Terry Cunniffe , Disabilities Resource Centre , Palme rston North , Advisor ; Dr And r ew Davies , Department of Physiology and Anatomy , Massey University , for the loan of the equipment ; and the subjects , A . W. F . S . I. B . G . J . A. V. J . J . J . H. CHAPTER 1 Int roductio n " Manu a l Jabour , some times und e r adverse e nvironmental condi tions , stilJ exists in all coun tries , and will probably r e main an essential part of the society . Furthermore , individuals continue to find satisfaction a nd enjoyment in thei r leisure time through sports or other t ypes of muscular activity . . In a very broad sense , physical pe rfor mance or fitness is determined by the individual ' s capac ity for energy output (aerobic and anaerobic processes and oxygen transport) , neuromuscular function (muscl e strength , co- ordination and techn ique ) , joint mobility a nd psychologica l facto r s (e . g. mot i vation and tactics) These factors play a more or less domina ting rol e depending upon the nature of the pe r formance " (Astrand a nd Rodahl , 1977 , 7). So interest in the physical capacity of individuals to perform , whether at work o r l e isure , has increased in spite of a correspond ing increase in automation in the work place . Indeed Davis ( 197 7) doubts that automation will continue at the exponential level predicted . Davis (1 977) ident ified three stages of t echnological progress ; Primary ( simp l e ) , Secondary (complex , non human e nergy) and Te rtiary (fully automatic ) , a nd state d t hat during its formative years ergonomics had concerned itse lf with looking at Secondary systems . However the need to investigate primary technology is now perceived to be of increasing importance because of the - 2 -possibility of an initial rise in manual worker availability following the turn of the next century, followed by a rapid fall. The rationale for the pe rceived need for the redesign and improved knowledge of primary technology is that as energy suppli e s diminish there will be a n e e d to return to bioJogicaJ e ne rg y , 0 ut with the pr es0.nt l e v e ls of popul a tion the r e i s insufficie nt land to support any large increase s in horses or catt~ as alte rnative en e rgy sources. If, therefore, manual labour and othe r physical activities are to become the focus of future concentration it is necessary that we know as much as possible about work, the physical cost of work, the measure me nt of that cost , and how work can be efficient within the ph ysical limits of the individual. The objective '.) f this research report is to test some theoretical models d e ve loped to d e t e rmine physical performance , base d on he a rt r a te and oxygen consumption, against dire ct measures of thes e parameters . 1 • 1 Body Work and Energy The physi ol.~g y of muscuflar work and exercise is basically a matter c ~ ~ransforming bound energy into mechanical energy . Many similarities exist between the "human engine " and the combustion engine constructed by human beings. In the combustion engine peteroleum and air are introduced into the cylinder. The spark from the spark plug initiates the explosive combustion of the gas mixture. Chemical energy is transformed into kinetic energy and heat. - 3 -The expansion of the gas forces the piston to move , and a system of mechanical devices can transfer this motion to the wheels . The motor is cooled by fluid or air to prevent overheating . The waste products are expelled with the exhaust . As this motor can work on l y in the prcscnco of oxygon , its function is aerobic . Whe n the petrol tank is empty , the engine can no longe r continue to run , since the operation of the combustion engine is depe nden t upon a continuous supply of fuel. In a motorcar , the starter motor provides the energy for the first movements of the pistons . This energy comes from the oattery which accumulates electrical energy : the starter can thus work in the absence of oxygen , or anaerobically . The stored e n ergy of the battery is quite limited however , so the battery must be frequently recharged . " Living organisms , like machines , conform to the law of the conservation of energy, and must pay for a l l their activities in the currency of metabolism (Baldwin , 1967). In the human machine , the mu sc l e fibers ( s ic) arc the pjstons. When fuel is available and a spark is introduce d to start the breaking down of the fuel , part of the energy which is thus liberated can cause movement of the piston s. Heat and various waste products are produced " (Astrand and Rodahl , 1977, 12) . The energy needs of individuals are satisfied by food which the individual consumes during the course of a day . If the health and activity of individuals are to be maintaine d then a certain minimum amount of food must be consumed per day . - 4 -However, the probl e m aris e s of how to measure the amount of food consumed and what proportion of this food is converted into energy and us e d as such in the human e ngine . 1 • 2 Llir cc t Meas ure s of En e rgy Expe nditur e Obviously die tary studie s can be made of individual subjects and this has been att empte d in the past. The energy expenditure of a variety of occupations was stated after analysing the diets consumed by individuals of know employment (Voit et al, 1955). This me thod is ope n to the the oretical objection that it assumes that the di e ts consume d pr ov id e exactly enough energy with no surplus or defici e nc y (Passmore and Durnin 1955). It provides no direct yardstick or r equirement. Indeed, especially in developing countrie s large numbe rs of people certainly have an insufficiency of food for he alth and activity, whereas the high incidenc e of obe sity in We ste rn countries shows that many consume r e gularl y an e xce s s of food over their physical requirements. There is a real difficulty in converting the results of dietary surveys into tables of food requirements. Further, dietary surveys are always difficult and expensive to carry out. This particularly applies to individual surveys which provide so much more information than the less precise family surveys (Passmore and Durnin, 1955). - 5 -1 • 3 Indirect Measures of Energy Expenditure Alternatively, the use of rates of oxygen consumption as the basis for measuring e nergy expenditure has become wide ly used. 'This mc•t h od or mc,:isuring the mcit.1bo 1jc cos t or work, ,,1onq wi t h heart rate , is known as indire ct calorime try and has been increasingly used in field conditions, to a large part due to the d eve lopme nt of apparatus which may now be used in field conditions, ·vh ereas it was once impracticable to do this because of the cumbersome nature of the apparatus designed for studies in l abora tory conditions. Indire ct calorimetry enab l es the e n e rgy expende d to be determine whil e a definite activity is undertake n for a limited period of time, usually meas ur ed in minutes. In th e past indirect calorimetry and data collected using this method ha ve met with . only limited success , mainly due to the practical difficulties of determining oxyge n consumption in fi e ld s e ttings. The apparatus that was used in earlier atte mpts to establish energy expenditure at work was the Douglas Bag, the siz e of which made stud i es under field conditions very difficult and led to imprecis e data collection. The Dougla s Bag wa s more suited to static exercise, or treadmill running in the laboratory. However in the 1940's a light portable respirometer was developed at the Max-Planc-Institut fur Arbeitsphysiologie in Germany. The portable respirometer has several attributes in its favour over the Douglas Bag for experiments under field conditions. It is light, we ighs less than four kilograms; - 6 -it can be worn on the back like a haversack ; it measures the volume of expired air directly while simultaneously diverting a small fraction of the expired air (0.3 - 6%) into a rubber bladder for late r analysis (Passmore and Durnin , 1955) . Pas s mo re· ,1 nd Du,-nin (1 'ViS ) st:1tc' th,1t fir st m,1ior t0st o f t lw portable r esp irome t er wa s a survey of workers in German industry during World War two. e bservat ions we r e made of individuals only at work in the factories and the mines , but assumptions were made for e nergy expenditure outside working time and the results were e xpande d and expressed in t erms of daily energy requirements . Subsequent observations we r e carr ied out in Britain and from the se , tables of e nergy expenditure for given occupations and activiti e s have been compiled . It is inte r esting to note that even though the portable respirometer , and various modifications , has been in use for approximately forty years a t the time of writing, there is still a dependence on laboratory work wi th the Dougla s Bag. Whi le it may be assure d that the portable r esp irome t er would be technically superior a~d ~or e accurate tha n the Douglas Bag , Astrand and Rodahl ( 1 9-17 ) disagree . "The classical method for the dete rmination of oxygen uptake , the Douglas Bag method , rests on a very secure foundation . It is theoretically sound , and it is well tested under a wi<le variety of circumstances . In all its r elat i ve simplicity , it is unsurpassable in accuracy " (p. 339). Exampl es of the continued use of the Douglas na g may be seen in the work of Vokac et al (1975), Bergh et al (1976) , Goldsmith et al (1978) and Datta et al (1978). On the other hand Aunola et al (1978), Soule et al (1978), Saha et a l (1979) and Verma et al - 7 -(1979) used a portable r espirometer to collect expired air for analysis to determine e nergy expenditure in their experiments . It is felt that the measurement of oxygen consumption in order to csti miltc ;:i n indjvjJu,11 ' s c' nergy <'XPL' nuj turc c;:i n give rise to imprecision. An opinion is (Passmore and Durnin, 1955) that larger errors are like ly to arise from a failure to determine corectly the length of time spent in any activity rather than in any assessment of the metabolic cost of that activity. An exampl e of this is that if a man walks to and from his work eve ry day, it is essential to know how long he spends on the journey. Wh e n compared with his other activities the exact energy cost of the walking may be comparatively unimportant. Further, one measurement of such an activity is only strictly applicable to the walking while the measurement is being made. An accurate value for an individual's walking, in general, ne cessitates several estimations under a variety of environomental conditions (Passmor e and Durnin, 1955). For this reason one must seriously consider the implications of the use of oxygen consumption from which to measure individuals' energy expenditure . If, however, the alternative is direct calorimetry through a study of individuals' diets, then the measurement of oxygen consumption is preferable for research purposes . However it must be stressed thatno single tool exi sts than can measure the effects of different kinds of loads on an individual (Davis et al, 1969), which leads to a second physiological variable that must be examined: heart rate. - 8 -Hear rate is used to measure energy expenditure indirectly for a variety of reasons. It is less intricate and time consuming than the measurement of oxygen consumption, the use of which has been felt to retard progress in the determination of energy expenditure rtt wor k (T.c hL1nc, 19 57). Furth C' r, oxyge n consumption a lone is not a r e liable indicator of energy expenditure (Maxfiela and Brouha, 19 63). There is a linear relationship between heart rate and oxygen consumption (Astrand and Rodahl, 1977), and it is felt wise to me asure both heart rate and oxygen consumption since oxygen consumption alone would not indicate changes in temperature and humidity in the work e nvironment (Davis et al, 1969) . Finally, heart rate has been shown to be sufficiently accurate within the range of most industrial jobs (Ricci, 1967). However in his research the central concern is the cost of work and the capabilities and limitations of individuals. 

An investigation of the validity of a section of a theoretical model to predict work physiology parameters from age and weight : a research project presented in partial fulfilment of the requirements for the degree of Master of Business Studies at Massey University

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An investigation of the validity of a section of a theoretical model to predict work physiology parameters from age and weight : a research project presented in partial fulfilment of the requirements for the degree of Master of Business Studies at Massey University

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