_: E : THES1S LIBRARY Michigan State Universry ROOM use ONLY {1: am! @3631 ABSTRACT A COMPARISON OF FIVE MAXIMAL OXYGEN INTAKE TESTS by Franklin Lee Hartman Nine subjects were tested on five maximal oxygen intake tests. Maximal oxygen intake, maximal oxygen intake per kilogram of body weight, and heart rate were determined for each subject. Analysis of variance and Duncan's Multiple Range test were used to statistically test the data. It was found that there is a difference in the physio— logical response elicited by various maximal tests. A test on the treadmill (Taylor test 2) at 7 m.p.h. up a grade (increments of 2 1/2 per cent) gave the highest mean values for maximal oxygen intake, for oxygen intake per kilogram of body weight, and for heart rate. A bicycle ergometer test at 60 pedal revolutions per minute and various work loads (increments of 300 kg-m/min.) gave the lowest mean values for maximal oxygen intake, for oxygen intake per kilogram of body weight, and for heart rate. A COMPARISON OF FIVE MAXIMAL OXYGEN INTAKE TESTS BY Franklin Lee Hartman A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF ARTS Department of Health, Physical Education, and Recreation 1965 ACKNOWLEDGEMENTS The author wishes to express his sincere appreciation to Dr. William Heusner and Dr. Wayne Van Huss for their guidance in the preparation of this study. The author also wishes to express thanks to Deann LeBeau, John Blom, and John Frater for their help with data collection. ii TABLE OF CONTENTS Chapter I. INTRODUCTION . . . . . . . . . . . . . . . Statement of the Problem Scope of the Study Limitations of the Study Definitions II. REVIEW OF THE LITERATURE . . . . . . . . Selected Methods of Maximal Oxygen Intake . Determination III. METHODOLOGY. . . . . . . . . . . . . . . . Test 1 Cureton Test 2 Michael Test 3 Taylor 1 Test 4 Taylor 2 Test 5 Wahlund Warm-up Prior to Testing Measurement and Instrumentation Statistical Technique IV. ANALYSIS OF DATA . . . . . . . . . . . . . iii 10 10 10 11 ll 12 13 15 16 Chapter Page V . SUMMARY, CONCLUS IONS , AND RECOMMENDATIONS . . . 22 Conclusions 23 Recommendations 24 BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . 25 APPENDICES . . . . . . . . . . . . . . . . . . . . 28 iv LIST OF TABLES Table Page 1 Test Sequence. . . . . . . . . . . . . . . . 9 2 Mean Values for Nine Subjects on First Tests . l6 3 02 Intake. . . . . . . . . . . . . . . . . . l7 4 OZ/Kg/Min. . . . . . . . . . . . . . . . . . . 18 5 Heart Rate . . . . . . . . . . . . . . . . . l9 Figure Electrode Electrode Electrode Electrode Electrode LIST OF FIGURES Placement. Placement. Attachment Attachment Attachment vi Page 30 3O 3O 30 3O CHAPTER I INTRODUCTION For years, various investigators have been using "maximal oxygen intake tests" as a measure in their experi— ments. These tests have been used in longitudinal experi- ments as a measure of the effects of training programs and diets. They likewise serve as an indicator of physical capacity for work. From the literature (Astrand, Balke, Billings, Issekutz, Keys, Maritz, Michael, Cureton, Robinson, Wahlund, Wyndham Slonim, Taylor), it is evident that there are many differ- ent ways of determining maximal oxygen intake. Yet, these many methods have been derived from four basic methods, which are: 1. Stepping on a bench 2. Walking on a motor driven treadmill 3. Running on a motor driven treadmill 4. Riding a bicycle ergometer A comparison of all the maximal oxygen intake tests, by a single laboratory, on the same set of subjects would be a valuable, yet monumental, undertaking. For this reason, five tests were selected for this investigation. A treadmill and a bicycle ergometer were used. Speeds possible on the treadmill ranged from a slow walk to 10.5 m.p.h. Grade was variable from 0 to 13 per cent. On the bicycle ergometer, a maximum workload of 2400 kg-m/min. was possible. Statement of the Problem The problem was to determine which of the five maximal oxygen intake tests studied will elicit the highest value(s) from a specified group of subjects. Will this test (if there is one) also elicit the high- est heart rate? Scope of the Study, The study was limited to nine male volunteers between 18 and 24 years of age. Seven of the volunteers came from a Track and Field class. The remaining two subjects were graduate students in Physical Education. Only one of the two graduate students had previous experience in Track and Field. Limitations of the Study Size of the Sample—-Original plans called for the test- ing of twenty-six subjects. This number was reduced to nine; because of technical difficulties, and the length of testing time required for each subject. Psychological Factor-—In any maximal test, there arises the problem of obtaining a "maximal" performance from the subject being tested. Getting a "maximal" performance from the subjects was possible by encouraging them during the test. This was done by using the following phrases: "You are doing a real nice job," "We are getting a good record- ing," "You can go a little longer. Keep it going." When, by the subjective rating of the tester, any ride or run was deemed not to be maximal; the subject was re— tested on that particular test. Improvement of Running and Riding Techniques--Each subject was given one practice session before the actual testing sequence was started. During this practice session, the subject would run on the treadmill at all of the testing speeds and grades. Also at the practice session, each sub- ject rode the bicycle ergometer with varying workloads. The testing sequence was varied from subject to subject, thereby reducing the factor of learning to a minimum. Time Span of the Study--Subjects were tested three times weekly, except in cases where class scheduling interfered, thus allowing the testing sequence to be completed within three weeks. Time of Day--Each subject was tested each day as near the same time as possible. Weather Conditions-—Weather conditions remained nearly the same for the period of time necessary to complete the testing of each subject. Food and Tobacco--There was no attempt made to control the ingestion of food or the use of tobacco prior to testing. Definitions Maximal oxygen intake is defined as the highest value of oxygen removed from the inhaled air by the subject dur- ing any given period of gas collection. Heart rate is defined as the rate attained during the period of gas collection that elicited the maximal oxygen intake. CHAPTER II REVIEW OF THE LITERATURE Nearly every article dealing with maximal oxygen intake describes in detail the physiological phenomena involved. For that reason, this review will not deal with the causa— tive factors, but with comparative maximal oxygen intake studies and with the methodology of the specific tests that have been used in this study. For those desiring informa- tion on the factors affecting oxygen intake in maximal work, there is an excellent chapter by Henry Longstreet Taylor (26) that covers the topic thoroughly. Taylor, Buskirk, and Henschel (27) found that the oxygen intake value, deemed maximal when running on a treadmill, could be further increased if the person cranked a hand- ergometer while running on a treadmill. Cranking and run- ning values exceeded those obtained while only running by 200 cc/min. or more. They also found that by holding the treadmill grade constant (1.5 per cent) and increasing the speed while simultaneously cranking, the oxygen intake value was found to be higher than that obtained while running at any given speed. Astrand and Saltin (3), using seven subjects (six male and one female), compared seven different types of maximal exercise (leg work on a bicycle ergometer, arm plus leg work, running, skiing, leg work while cycling in supine position, swimming, and arm work on a bicycle ergometer). They found that running uphill produced a higher maximal oxygen intake value than the other types of exercise examined. Observa- tions were made that the maximal heart rate was nearly the same in all types of exercise. Newton (19) compared four maximal tests (Balke, Cureton, bicycle, and standard treadmill run) and found that the highest oxygen intake values were obtained with either the Balke test or with the standard treadmill run. A trained bicyclist was able to obtain an oxygen intake value while cycling that was nearly as high as for a standard treadmill run. A trained distance runner achieved a maximal figure for the Cureton run which was very near that of the tread— mill run. No data were given for heart rate. Selected Methods of Maximal Oxygen Intake Determination Cureton (8) says of maximal tests, The test need not have to be a test at the very fastest running speed, but it must be a "maximal" test which will overload the circulatory-respiratory capac- ity enough to bring about complete exhaustion within 5 minutes or less . . . . At about 7 miles per hour, 8.6 per cent grade, treadmill running, an ordinary healthy young man will develop approximately maximal blood flow. At rates of speed above 7 miles per hour all but the best athletes will "tense-up," and the blood flow through their arms and legs and through the total heart-lung circuit will be impeded, thus causing them to "tie-up" sooner than if they were able to hold a normal full running stride with good relaxation throughout the run. The optimum test for the top athletes is probably at 10 miles per hour, 8.6 per cent grade. Cureton used a treadmill run of 10 miles per hour, 8.6 per cent grade. Twenty champion athletes were tested, but all were not runners (swimmers, wrestlers and others were also included). Gas was collected throughout the run in l or 2 large bags as needed. Oxygen intake values ranged from 1.770 to 4.160 liters per minute, with a mean of 2.765 liters. Michael, Hutton, and Horvat (17) using a test closer to that recommended by Cureton for "an ordinary healthy young man," tested three subjects (the subjects lived on a regu- lated diet and lived in an air conditioned environment of 20-23 degrees Centigrade, 50 per cent relative humidity), and obtained maximal oxygen intake values of 4.06, 4.11, and 4.31 liters per minute. The test used was a treadmill run at 7 miles per hour up an 8.6 per cent grade, "until exhaustion (4-5 min.)." Taylor, Buskirk, and Henschel (27) used a treadmill run at 7 miles per hour at various grades (increments of 2 l/2 per cent). The run was of 3 minutes duration, with gas collection being made between 1 minute and 45 seconds and 2 minutes and 45 seconds. The grade for the first test session was determined by the treadmill version of the Harvard Fitness Test. On the second test session (third visit), . . . the procedure was repeated with the subject run- ning on a grade 2.5% higher than had been employed on the second visit [first test session]. If the two oxygen intakes were different by less than 150 cc/kg/ min. the working conditions were considered to have elicited a maximal oxygen intake. If a larger positive difference occurred, a fourth visit to the Laboratory was required and the 3-minute run was carried out at a grade which was again increased by 2.5%. The procedure was repeated until two grades were found which resulted in oxygen intakes which met the established criterion. Wahlund's bicycle ergometer test (28) was designed "to find the usefulness of standardized tests for judging patients with heart and lung diseases." Work was performed at a pedal rate of 60 revolutions per minute. The test was as follows: . . . an uninterrupted series of work loads beginning with 300 or 600 Kg-m/min., and increasing at approxi- mately every 6 1/2 min. by 300 Kg—m/min., until the subject could not go on any longer, or until the work at 1200 Kg-m/min. was accomplished . . . . Ventilation of lungs and 02 consumption was determined by D. bag method for 2 1/2 min. from the 4th minute. CHAPTER III METHODOLOGY A group of nine male volunteers between 18 and 24 years of age were tested on five maximal oxygen intake tests. Subjects were tested on a Monday, Wednesday, Friday schedule, except in the case of two subjects whose class schedules would not allow this. They were tested on Tuesday and Thursday. The nine subjects served as their own controls, being tested on all five tests. The test sequence was not the same for each subject, thus eliminating sequence bias. The test sequence is shown in Table 1. TABLE 1 TEST SEQUENCE Subject A B C D E F G H I Test 1 2 3 4 3 4 2 l l 10 Test 1 Cureton The test consisted of running on the treadmill at 10 m.p.h. up an 8.6 per cent grade until the subject could no longer maintain pace. EKG recording (heart rate) and gas collection were started at 30 seconds or at a heart rate of 170 beats per minute, whichever came first. Test 2 Michael The subject ran on the treadmill at 7.5 m.p.h. with grade set at 8.6 per cent grade. The test was terminated when the subject could not maintain the pace. The gas collection and EKG recording were started at 2 minutes or at a heart rate of 170 beats per minute, whichever came first. Test 3 Taylor 1 (a modification of Taylor's test) The treadmill was set at 7 m.p.h. during this test. The grade was varied as described below. The first day this test was administered, the subject ran at a 5 per cent grade for three minutes. If the subject completed the three minute run at 5 per cent grade, the grade was raised to 7 1/2 per cent for the text testing session. This procedure was continued at 10 per cent and 12 1/2 per cent grades, if the subject had completed the three minutes on the preceding visit and if the two preceding oxygen ll intake values varied by more than 150 ml. (the same cri- terion used by Taylor for determination of maximal oxygen intake). EKG recordings and gas samples were taken from 1 minute 45 seconds to 2 minutes 45 seconds during each run. This test is a slight modification of Taylor's test. The modification being that no prediction was made as to what grade would yield the maximal oxygen intake. This prediction by Taylor was made with the help of the tread- mill version of the Harvard Fitness Test. Test 4 Taylor 2 (a modification of Taylor's test) The speed was set at 7 m.p.h. The grade started at 0 per cent for the first two minutes. At the end of two minutes, the grade was raised to 2 1/2 per cent. Thereafter, the grade was increased by 2 1/2 per cent every two minutes until the subject could no longer maintain pace. Gas collection and EKG recording started at a heart rate of 170 beats per minute and continued to termination. Test 5 Wahlgnd (a modification) A bicycle ergometer was pedaled during this test at 60 r.p.m. The initial workload was 600 kg-m./min., and the load was increased by 300 kg-m./min. every three minutes 12 until the cyclist could no longer remain reasonably close to the prescribed pace (this was a subjective judgment on the part of the tester). Pace was given by an electric metronome. A revolution counter gave a means of checking on the rate of work. In all cases, pace was maintained nearly perfectly until near the end of the ride. The tester, having never administered tests on a bicycle ergometer, found it necessary to use subjective judgment in deciding when the subject was nearing the end of the ride. The same subjective judgment was used in determining when to begin the EKG recording and gas collection. In no case did the first bag of gas collected yield the highest 02 intake value. Warm—up Prior to Testing The warm-up period prior to all of the treadmill tests consisted of a five-minute bout of exercise on the level treadmill at 6 m.p.h. This was followed by a five-minute .rest period, in all tests except Test 4. Test 4 began immediately following the warm-up period. .Warm—up for the bicycle ergometer consisted of five minutes of cycling at 60 r.p.m. with the workload set at 13 450 kg-m./min. This was followed by a five—minute rest period. As many authors (Astrand, Issekutz, Keys, Slonim, Taylor, Wyndham) have used a warm-up prior to the administration of maximal tests, it was decided to use a standard warm-up prior to all tests. Likewise, it was decided to use a standard rest period, except in the case of Test 4. Thus, one possible source of variation between tests was elimi- nated by the standardized warm-up and rest periods. Measurement and Instrumentation Heart rates, respiration rates and gas samples were collected while the subject exercised in an air conditioned room. The equipment used for this purpose is very aptly described by Stolberg (24) as follows: . . . Glass electrodes1 were applied to the subject as indicated in Appendix D. The heart beat was amplified and monitored by a Sanborn Twin-Viso Recorder from which the signal was then relayed to a Sanborn Cardio- Tachometer and the changes were recorded on a Sargent SR Recorder providing a continuous permanent record of heart rate. Oxygen consumption of the subjects during the tread- mill test was determined by the use of an open circuit energy metabolism system. The inspiratory and expira— tory resistances in the circuit used were less than 20 mm. H20 at flow rates up to 225 1/min. Expired air was collected during 30 second intervals in fifty-liter plastic Douglas bags. A sample from each bag was analyzed for percent oxygen and carbon dioxide by Beckman Elec- tronic Analyzers (E-2 Oxygen Analyzer, LB-lSA Carbon 14 Dioxide Analyzer). The gas volume was then measured by a Franz-Muller Calorimeter. Oxygen consumption figures were calculated by methods described by Consolazio, Johnson and Pecora (l, p. 16). Figure 3 schematically shows the gas collection and analysis system . . . . The experimental design called for approximately 15- second samples of gas throughout the collection period, rather than the exact 30-second samples collected by Stol- berg. Exact lS-second samples were not used, as gas col- lection bags were switched on inspiration. 02 intake values were corrected to minute values. Heart rate values were also corrected to minute values for the period corresponding with maximal oxygen intake. Electrode placement and method of attachment are shown in Appendix B. Work was performed on a motor driven treadmill and a bicycle ergometer. The treadmill was built by the A. R. Young Company. Performance capabilities are as follows: Speed--Slow walk to 10.5 m.p.h. Grade--O per cent to 13 per cent The bicycle ergometer is like that described by Karpo- vich (14). A calibration scale was derived using the method described by Karpovich (l4) and by Royce and Henry (21). 15 Statistical Technique An analysis of variance was run on the data. The results are presented in Chapter IV. The raw data is presented in Appendix A. CHAPTER IV ANALYSIS OF DATA The purpose of this study was to determine whether or not there were any differences in the physiological re- sponses produced by a selected number of tests used for determination of maximal oxygen intake. Table 2 gives the mean values for the 9 subjects on the 5 tests. TABLE 2 MEAN VALUES FOR NINE SUBJECTS ON FIVE TESTS Test Name 02 L/Min. O2 L/Kg/Min. Heart Rate 1 Cureton 4.02 t .33 0.0578 t .0047 186 1 8.1 2 Michael 4.09 i .42 0.0588 t .0058 187 i 6.6 3 Taylor 1 4.25 i .26 0.0614 t .0075 186 i 7.0 4 Taylor 2 4.29 i .48 0.0615 t .0067 192 i 5.7 5 Wahlund 3.54 i .36 0.0513 1 .0103 181 i 8.6 From the mean values obtained, there do appear to be differences in the physiological responses elicited by the various tests. Analysis of variance was used to statisti- cally analyze these differences. The Duncan Multiple Range Test (23) was employed after the analysis of variance. Table 3 represents the analysis of variance table for oxygen intake. The table shows that Taylor test 2 produced a significantly greater oxygen intake than Cureton's and 16 Wahlund's at the .01 Michael‘s at the .05 difference in oxygen test 1. Taylor test Wahlund's at the .01 the .05 level, while intake than Michael's test. 17 level of significance, level. Statistically, and greater than there is no intake between Taylor test 2 and Taylor 1 produced a greater oxygen intake than level, and greater than Cureton's at it did not produce a greater oxygen Michael's test produced a greater oxygen intake than Wahlund's at the .01 level, while it did not produce a greater oxygen intake than Cureton's. Cureton's test produced a greater oxygen intake than Wah- lund's at the .01 level. Source of Variance Between tests Between individuals Residual TABLE 3 O2 INTAKE SS DF 32,239.91 4 20,274.78 8 36,343.89 32 Total 88,858.58 44 Tests Level Tests 4 vs 5 4 > 5 .01 3 vs 4 vs 1 4 > 1 .01 3 vs 4 vs 2 4 > 2 .05 2 vs 4 vs 3 4 3 N.S. 2 vs 3 vs 5 3 > 5 .01 1 vs UlI-‘U'INH MS 8,059.98 2,534.35 1,135.75 Ull-‘UlNH Level .05 N.S. .01 N.S. .01 18 TABLE 4 OZ/KG/MIN. Source of Variance SS DF MS F Between tests 62,582.80 4 15,645.70 5.92 Between individuals 117,900.44 8 14,737.56 Residual 84,552.00 32 2,642.25 Total 265,035.24 44 Tests Level Tests Level 4 vs 5 4 > 5 .01 3 vs 1 3 > 1 .05 4 vs 1 4 > 1 .05 3 vs 2 3 2 N.S. 4 vs 2 4 2 N.S. 2 vs 5 2 > 5 .01 4 vs 3 4 3 N.S. 2 vs 1 2 l N.S. 3vsS 3)5 .01 lvsS 1>5 .01 Table 4 represents the analysis of variance table for oxygen intake per kilogram of body weight. The table shows that Taylor test 2 produced a significantly greater oxygen intake per kilogram of body weight than Wahlund's at the .01 level of significance, and greater than Cureton's at the .05 level, while it did not yield greater values than those produced by Taylor test 1 or Michael's test. Taylor test 1 produced a greater oxygen intake per kilogram of body weight than Wahlund's at the .01 level, and greater than Cureton's at the .05 level, while it did not yield greater values than those produced by Michael's test. Michael's test produced a greater oxygen intake per kilogram of body weight than did . 19 Wahlund's at the .01 level, while it did not yield greater values than those produced by Cureton's. Cureton's test produced a greater oxygen intake per kilogram of body weight than did Wahlund's at the .01 level. Table 5 represents the analysis of variance table for heart rate during the time of maximal oxygen intake. The table shows that Taylor test 2 produced a significantly greater heart rate than the other four tests at the .01 level of significance. Michael's test produced a greater heart rate than Wahlund's at the .01 level, while it did not pro- duce a greater heart rate than Cureton's or Taylor test 1. TABLE 5 HEART RATE Source of Variance SS DF MS F Between tests 609.33 4 152.33 4.75 Between individuals 1,110.18 8 138.77 Residual 1,024.27 32 32.01 Total 2,743.78 44 Tests Level Tests Level 4 vs 5 4 > 5 .01 2 vs 1 2 1 N.S. 4 vs 1 4 > l .01 2 vs 3 2 3 N.S. 4 vs 3 4 > 3 .01 3 vs 5 3 > 5 .05 4 vs 2 4 > 2 .01 3 vs 1 3 l N.S. 2 vs 5 2 > 5 .01 1 vs 5 1 > 5 .05 20 Taylor test 1 produced a greater heart rate than Wahlund's at the .05 level, while it was not greater than the heart rate produced by Cureton's. Cureton's test produced a greater heart rate than Wahlund's at the .05 level. From the data presented, one may say that under these working conditions, with this group of subjects, there do exist differences in the physiological responses produced by the tests compared. Taylor test 2 is significantly greater than all but Taylor test 1, with reference to oxygen intake. Taylor test 2 was greater than Cureton's and Wahlund's tests, with respect to oxygen intake per kilogram of body weight. Taylor test 2 produced a greater heart rate than any of the other tests. Taylor, Buskirk and Henschel (27) concluded "that the maximal oxygen intake is only maximal for specified working conditions." This conclusion would hold true for the data presented. The data presented in this chapter are clearly in accordance with those presented by Newton (19). Newton found that the bicycle ergometer test and Cureton's test gave lower values when compared with a standard treadmill run (the treadmill run was similar to that used by Taylor) and Balke's treadmill test (walking at 5.4 K/hr.). 21 Astrand and Saltin (3) demonstrated a difference be- tween tests (leg work on a bicycle ergometer, arm plus leg work, running, skiing, leg work while cycling in the supine position, swimming, and arm work on a bicycle ergometer) with Taylor's test giving the highest values for oxygen intake. The statistical work is not clearly presented. CHAPTER V SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS Nine subjects were tested on five maximal oxygen intake tests. Maximal oxygen intake, maximal oxygen intake per kilogram of body weight, and heart rate were determined for each subject. Analysis of variance and Duncan's Multiple Range test were used to statistically test the data. The following results were obtained. Cureton's test consisted of a run to exhaustion on a motor driven treadmill at 10 m.p.h. up an 8.6 per cent grade. Means obtained: oxygen intake, 4.02 liters per minute; 0.0578 liters of oxygen per kilogram of body weight per minute; heart rate, 186 beats per minute. . Michael's test consisted of a treadmill run at 7 1/2 m.p.h. up an 8.6 per cent grade to exhaustion. Means obtained: oxygen intake, 4.09 liters per minute; oxygen intake per kilogram of body weight per minute, 0.0588; heart rate, 187 beats per minute. Taylor test 1 consisted of a 3 minute run on a tread- mill at 7 m.p.h. up a grade of 2 1/2, 5, 7 1/2, 10, or 12 1/2 per cent. Means obtained: oxygen intake, 4.25 liters per minute; oxygen intake per kilogram of body weight per 22 23 minute, 0.0614; heart rate, 186 beats per minute. Taylor test 2 consisted of a run to exhaustion on a treadmill at 7 m.p.h. The grade was raised 2 1/2 per cent at the end of each 2 minutes, with the run starting at 0 per cent. Means obtained: oxygen intake, 4.29 liters per minute; oxygen intake per kilogram of body weight per minute, 0.0615; heart rate, 192 beats per minute. Wahlund's test consisted of a bicycle ergometer ride at 60 pedal revolutions per minute to exhaustion. Work load started at 600 kilogram-meters per minute and was increased by 300 kilogram-meters per minute at the end of every 3 minutes of the ride. Means obtained: oxygen intake, 3.54 liters per minute; oxygen intake per kilogram of body weight per minute, 0.0513; heart rate, 181 beats per minute. Conclusions 1. There is a difference in the physiological response elicited by the tests compared. 2. Taylor test 2 gave the highest mean values for maxi- mal oxygen intake, for oxygen intake per kilogram of body weight, and for heart rate. 3. Wahlund's test gave the lowest mean values for maximal oxygen intake, for oxygen intake per kilogram of body weight, and for heart rate. 24 4. Maximal oxygen intake is maximal only for a particular set of conditions. Recommendations I would recommend the following to others contemplating studies of this nature. 1. Increase the rate of pedaling for bicycle ergometer tests to 70 or 80 pedal revolutions per minute. 2. Some maximal treadmill walking tests should be used in a comparison with running tests and bicycle ergometer tests. 3. Subjects for a study of this nature should take part in a training program of several weeks duration. 4. There should be some type of control over the food intake (amount and type) and the use of tobacco and alcohol prior to testing. 10. BI BLIOGRAPHY Astrand, P. 0., Experimental Studies of Physical Work— ing Capacity in Relation to Sex and Age, Copenhagen, Ejnar Munsgaard, 1952. Astrand, P. O., Ryhming, I., "A Nomogram for Calcula- tion of Aerobic Capacity (Physical Fitness) from Pulse Rate During Submaximal Work," Journal of Applied Physiology, 7:218, 1954. Astrand, P. 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C., The Multi Level Step Test as a Predictor of Maximum Oxygen Intake, Thesis, Michigan State University, 1964. Strydom, N. B., "Methods for Assessing Work Capacity," Not Published. Taylor, H. L., "Exercise and Metabolism," Science and Medicine of Exercise and Sports, New York, Harper Brothers Publishers, 1960. Taylor, H. L., Buskirk, E., Henschel, A., "Maximal Oxygen Intake as an Objective Measure of Cardio— Respiratory Performance," Journal of Applied Physiology, 8:73, 1955. Wahlund, H., "Determination of the Physical Working Capacity," Acta Medica Scandinavica, 132: Supp. 215, 1948. wyndham, C. H., Strydom, N. B., Maritz, J. S., Morrison, J. F., Potgieter, J. P., Potgieter, Z. U., "Maximum Oxygen Intake and Maximum Heart Rate During Strenuous Work," Journal of Applied Physiology, 14:927, 1959. 28 Hma omH wma 05H oma wha mma aha Hma 05H ammo. memo. mmno. omso. 6mmo. Heso. osso. maso. osmo. 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