Virginia Tech€¦ · readily detectable through measurement of breath-by-breath respiratory gas...

THE B.ELitl1 ION OF .ANAEROBIC THI1ESHOLD,

CIRCULORESPL"f=!ATORY ENDURAi.\l'CE AND

PERFOfu\lf AN CE CAP .A.CITY IN

ACTIVE ADULT MEN " '",.,

by

J h ""'d ; ~-0 n l!. w _n\\rtarp e::;:"

Thesis submitted to the Graduate Faculty of the

Virginia Polytechnic Institute and State University

in partial fulfillment of the

requirements for the degree of

MP..ST&-q OF SCIENCE

in

Education

APPROVED:

--~---~-------------------W~ G. Herbert, Chairman

--~--------..,.--------------- -------------------------D. R. Sebolt H. E. Robertshaw

May, 1979

Blacksburg, Virginia

ACKNOWLEDGMENT

For my wife , whose encouragement, support and

understanding was instrumental in the completion of this work.'

ii

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES • • • • • • • • • • • • • • 19: ': • ,. • •

• • • • • • • • • • • • • • • • • • •

Chapter

l •' INTRODUCTION . . . . . . . . . . . . ~ . . . STATEMENT OF PROBLEM • • • • • • • • • • • JUSTIFICATION • • • • • • • • • • • • • • • HYPO'?H!SES

DEFINITIONS

SYMBOLS

• • • • • • • • • • • • • • • •

• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

2. REVIEW OF LITERATURE • • • • • • • • • • • • TESTS OF CIRCULORESPIRATORY ENDURANCE

AND PERFORMANCE CAPACITY .... • • INTEBPLAY OF .AEROBIC AND AN.AEROBIC

MEI' ABOLISM • • • • • • • • • • • • ME'rABOLIC AND PULMONARY GAS EXCRANGE

CH.ARACT~ISTICS .ASSOCIATED WITH THE ANAEROBIC THBESHOLD • • • • • • • •

• • •

. . •·

• • • SUMMARY • • • • • • • • • • • • • • • • • •

3• MEI'HODOLOGY SUBJECTS

PROCEWBES

•· . . . . . . . . . . . . . . . . • • • • • • • • • • • • • • • • • . . . . . ~ . . . . ~ . . . . .

Preliminary . .. . . ~ . . . . . .. ~ •· . . Protocol tor the Experimental

Testing Series • • • • • . . .. • • • • Parameters . •· . . . . . . . . . . . . .

iii

Page

vi

vii

1

2

3 4

5

7 8

8

14

16 21

24

24

25 25

27

27

Chapter

INSTRUMENTATION . . . ~ . ; . . . . - . . . . . . TEST DESIGN • • • • @ • • • • • • • • • •

Protoco1 for Trials • • • • • •• • • • •

Determination of AT • • • • • • • • • • D.ATA .ANALYSIS • • • • • • • • • • • • • •

4. RESULTS • • • • • • • • • • • • • • • • • • AT BELIABILITY • • • • • • • • • • • • • • AT VALIDITY • • • • • • • • • • • • • • •

AT versus to2 max . . ' . . . . . . . . . AT versus Astrand• s Prediction

Page

28

29 29

33

35 36

36

38 38

of '0'92 max • • • • • • • • • • • • • • 45 AT versus Pwc170 •••• AT versus 1. 5 mi run • •

• •

• •

• • • • • •

• • • • • •

45 46

5. DISCUSSION • • • • • • • • • • • • • • • • • 47 AT RELIABILITY

AT V .ALIDITY

• • • • • • • • • • • • • •

• • • • • • • • • • • • • • •

AT versus VOz max • • • • • • • • • • • AT ve~sus Astrand's Prediction

47 50

5o

of v~ max • • • • • • • • • • • • • • 53

AT versus PWCi,70 • • • .. • • • • • • • • AT versus 1.5 mi run • • • • • • .. • • •

CONCLUSIONS • • • • • • • • • • • • • • •

IMPLICATIONS • • • • • • • • • • • • • • • RECOMMENDATIONS • • • • • • • • • • • • •

LITERATURE CITED • • • • • • • • • • • • • • • • •

1V

55

59

59 62

63

Chapter

.APPENDIXES • • • • • • • • • • • • • • • • • • • • •

A.

B.

c.

• It Summary of Individual Descriptive Measures

Experimental Testing Series ••••••

V02 max Prediction from the 1.5 mi run •

• • •

• • •

Page

66

66

67

68

D. Br~.ath-by-breath Techniques in Assessing V02@Jf! • • • • • • • • • • • • • • • • • • 69

E.

VITA

Individual Raw Data • • • • • • • • • • • • •

• • • • • • • • • • • • • • • • • • • • • • • •

v

71 72

LIST OF TABLES

Table

1. Summary of Descriptive Measures • • • • • •

Page

26 2. Incremental Workload Stages for PWc170 • • • JO

4.

5.

Summary of Statistical Measures for Repeated Kr Trials • • • • • • •

Summary of Statistical Measures for Functional and Performance Trials

• • • • •

• • • •

Coeff 1cients of Validity for Kr Comparison •

vi

42

43 44

Figure

1.

2.

LIST OF FIGURES

Anferobic Threshold Determination from Ve Exercise Intensity curves ••••

Line of Regression for Scatter Plot of Exercise Intensity Measurements at K!

3•' Line of Regression for Scatter Plot of

Page

• • • 34

·- . . 37

Oxygen Uptake Measurements at .AT • • • • • 39

6.

Line of Regression for Scatter Plot of Minute Ventilation Measurements at Pl!

Line of Regression for Scatter Plot of Heart rate Measurements at .AT ••••

The Result of .Asymptotic Effects on the Relationship Between Heart Rate and Oxygen Consumption • • • • • • • • •

Mean Differences Between Parameters for Trials of Function Capacity and Endurance Performance • • • • • .. •

vii

. -· . 40

• • • 41

• • •

• • • 54

Chapter l

INTRODUCl'ION

Exercise physiologists have and always will be

interested in accurately measuring and defining physio-

logical characteristics that are related to physical

performance. One area of specific interest has been the

efficiency and capacity of the circulorespiratory system

as it relates to performance (physical fitness).

Many tests have been devised to measure circulo-

respiratory function and performance capacity through

measurements of maximal oxygen uptake ('O'o 2 max) or • physiological parameters closely associated with vo2 max.

However, investigators have recently introduced a new

measure (anaerobic threshold, AT) for examining physical

performance using aerobic/anaerobic mechanisms.

Whipp, Seard and Wasserman (1970), Whipp and

Wasserman (1972) and Wasserman, Whipp, Koyal and Beaver (1973) were first to introduce and examine procedures for

rapidly determining the onset of metabolic acidosis during

exercise. Their investigations have shown that the rising

level of metabolic acidosis reflected by rapidly decreasing

plasma pH during nonsteady-state exercise can be used as an

indicator of anaerobic threshold. Wasserman and

co-workers ( 1973) have reported that these shifts are

1

2

readily detectable through measurement of breath-by-breath

respiratory gas exchange using fast response respiratory

gas analyzers.

Wasserman et al (1973) used breath-by-breath analysis

of expired airflow for C02 and 02 tensions at the mouth to

measure: ( 1) minute ventilation (Ve), ( 2) carbon dioxide

production (VC02). (3) oxygen uptake (V02) and (4) the gas

exchange ratio ( R). From these measures the Kr was

determined by the following simultaneous measurements:

{1) a nonlinear increase in Ve, (2) a nonlinear increase . in VC02, (3) an increase in Rand (4) an increase in end-

tidal 02 without a corresponding decrease in end-tidal C02.

Nevertheless, they hypothesized that the easiest method

for detecting Kr would be to measure -(re during an

incremental exercise test and look for the point at which s

the Ve exercise intensity curve becomes nonlinear.

ST .ATEMENT OF PROBLEM

• Using Ve exercise intensity curves for determining

Kr identifies a simple and bloodless method for examining

circulorespiratory endurance and performance capacity in

relation to aerobic/anaerobic measurements. 'rhis implies

that Nr may represent an alternative to the nearly exclusive • use of V02 max in the examination of physical performance.

However, there is no evidence to suggest that this

3

technique of ~.AT determination is either reliable or that

relationships exist between AT a.nd standard measures of

functional and performance capacity. Therefore, it is the

purpose of this investigation to identify the relative

merit of using AT as a possible index of circulorespiratory

endurance and/or performance capacity.

JUSTIFICATION

There appear to be several advantages for utilizing

.AT as an alternate or supplemental index of circulo-

respiratory endurance and/or performance capacity.

First, the use of AT may significantly reduce risks

associated with exercise prescription used in cardiac

rehabilitation programs by decreasing the time spent

exercising at high stress levels. Studies by Nairn.ark,

Wasserman and Mcilroy ( 1964) and Wasserman and r1cilroy ( 1964)

using measurements of R to detect anaerobic ~etabolism in

heart diseased patients during exercise support this

contention by indicating that potentially hazardous levels

of exercise could be avoided by terminating tests at the

onset of anaerobic metabolism.

For this reason, when the purpose of the exercise

test is for exercise prescription rather than medical

diagnosis the use of .Kr may allow an increased margin of

safety when assessing the exercise tolerance of cardiac

4

patients, yet allow sufficient taxing of the aerobic

processes to permit valid estimation of a training intensity

that would assure an adequate stimulus necessary to cause

circulorespiratory adaptations.

Secondly, the use of .Nr may specifically define and

measure functional and performance capacities in relation

to their aerobic/anaerobic characteristics. For example,

performance capacity may be defined as the work produced

by an individual at the maximum level of aerobic function;

where. the maximum level of aerobic function is define<:!

as that point in exercise when metabolism shifts from

aerobic to anaerobic processes (AT).

Thirdly, the use of AT :nay be a potentially valuable

method of evaluating training programs designed to modify

aerobic/anaerobic functions; e.g. comparing the effects

of training programs for sprinters, middle-distance

runners and distance runners. In addition, it might assist

researchers in identifying metabolic characteristics which

distinguish elite performance.

Lastly, the use of AT may reduce limitations associated

with direct and indirect measurement of vo 2 max.

HYPOTHESES

Using nonlinear changes in the Ve-exercise intensity

curve to predict AT: (1) There will be no difference between

5

measurements of AT in repeated tests of graded exercise for

active adult men and ( 2) There will be no independence between

corresponding measurements of AT and measurements of maximal

oxygen uptake, physical working capacity and field

measurements of circulorespiratory endurance.

DEFINITIONS

Aerobic metabolism: refers to the condition in the hUllla.n

body when oxygen supplies to the cell are adequate

for oxidation of fuels used to produce energy

Anaerobic metabolism: refers to the condition in the

human body when oxygen supplies to the cell are not

adequate in maintaining the oxidation of fuels

require~ to produce energy

.Anaerobic threshold: refers to the\ point during exercise

at which the majority of the body's metabolism

characteristics shift from aerobic to anaerobic

processes

Arteriovenous oxygen difference: refers to the difference

between oxygen content of the blood entering and

leaving the pulmonary capillaries

Carbon dioxide production: refers to the volume of CO 2

eliminated from the lungs during g;aseous exchange

Circulorespiratory endurance: refers to the ability of

the cardiovascular and respiratory systems to maintain

6

the delivery of oxygen to working tissues of the body

Gas exchange ratio: refers to the ratio of carbon dioxide

produced to the oxygen consuned

Lactic acid: refers to the by-product of glycolysis, + formed by the addition of H to pyruvic acid

Maximal oxygen uptake: refers to the greatest amount of

oxygen a person consumes during physical work

Maximal exercise tests: refers to exercise tests which

require work outputs of 90-100% capacity

Metabolic acidosis: refers to the condition in the human

body when metabolic activity creates a reduction in

the normal pH level of the blood

Metabolic equivalents: refers to a classification of work

output representing 3.5 ml 02 per kilogram of body

weight (METS )

Minute ventilation: refers to the volume of air introduced

into the lungs for gaseous exchange during a time

interval of one minute

Nicotinamide Adenine Dinucleotide: refers to a coenzyme

which acts to accept free hydrogen ions during

metabolic oxidation

Oxygen debt: refers to the amount of oxygen required at

the end of exercise to reverse anaerobic reactions

produced during exercise

Oxygen deficit: refers to the difference between oxygen

7

consumed during exercise and the amount required if

the supply of all energy was via aerobic reactions

Oxygen uptake: refers to the volQ~e of oxygen extracted

from the expired air

Performance capacity: refers to an individua1 1 s ability

to sustain maximal work

Submaximal exercise tests: refers to exercise tests that

require work outputs in the range of .50-90% of the

estimated maximal capacity

SYMBOLS

Kr: anaerobic threshold

a-V?2 diff: arteriovenous oxygen difference

co2 : carbon dioxide

HR.: heart rate

MEr: metabolic equivalents

NAD: N1cotinamide Adenine Dinucleotide

02: oxygen

PETC02: pressure of end-tidal carbon dioxide

PEr02: pressure of end-tidal oxygen

PWC: physical working capacity

R: respiratory gas exchange

, vw.. ~· volume of expired air per unit t i::r.e

• vco 2= volume of carbon dioxide produced per unit . VO 2: volume of oxygen consumed per unit time

time

Chapter 2

REVIEW OF LITERATURE

The development of .Kr was the combined result of

researchers attempts to: (1) reduce limitations associated ..

with direct and indirect measurement of vo 2 ma:x: used in

assessing circulorespiratory endurance and performance

capacity, (2) increase their understanding of the interplay

of aerobic/anaerobic functions in relation to physical

performance and (3) define anaerobic parameters and improve

technology for rapidly measuring them as they relate to

changes in aerobic and anaerobic functions during exercise.

TESTS OF CIRCULORESPIR.ATORY ENDURANCE AND PERFORMANCE CAPACITY

Perhaps the least controversial method of assessing

circulorespiratory endurance is through direct measurement

of maximum oxygen uptake. Astrand (1952) and Taylor, \

Buskirk and Henschel (1955) were among the first to measure

the maximal oxygen uptake under conditions of complete

exhaustion. This exhaustive technique enabled their

subjects to attain maximal levels for aJ.l indices ( 1. e.

heart rate, ventilation and oxygen uptake). Cooper { 1969)

and Detry ( 1973) suggested that the vo2 max test (described

by Taylor1i Buskirk and Henschel; 195.5) represented the

8

9

capacity of the oxygen transport system, from which

maximal vo2 values were accepted as the most vaJ.id indicator

of overall circulorespiratory function and performance

capacity. Taylor, Buskirk and Henschel (1955) used a

longitudinal (one year) study to establish test reliability • for maximal testing •. They found that their vo2 max test

produced a reliability coefficient of r=.95, p ~·. 05 for

69 test-retest determinations.

Nevertheless, there were important physiological and

possibly psychological limitations associated with the

direct measurement of vo2 max and its representative use as

an index of circulorespiratory endurance. Physiologically: • V02 max._ was limited through interactions with maximal heart

rate, stroke volume at the maximal exercise level and the

maximal. a.rteriovenous oxygen difference (Detr;y,· 1973) • • Furthurmore, tests of vo2 max required strenuous levels of

exercise that necessitated the concomitant participation of

aerobic and anaerobic processes; thus,' 1t may be agreed

that V02 max was not truely identifying the point of maximum

circulorespiratory efficiency (physical fitness) but rather

the peak c1rculoresp1ratory response under a supra-maximal

activity level, the attainment of which was partly ' dependent upon anaerobic mechanisms.

In addition, the strenuous exercise design of the test

introduced potential limitations associated with psychological

10

demands. 'I'wo such limitations were: ( 1) lack of motivation

and (2) perceived risks associated with strenuous exercise.

Subjects who lacked motivation had difficulty 1n achieving

maximal efforts. Shephard ( 1969) indicated that this was

especially true when testing sedentary individuals,' women

and older persons.' Also limiting maximal performance was

the subject •s perception of potential physical harm

associated with strenuous exercise. Although Rochmis and

Blackburn ( 1971) found the death rate to be as low as

1 per 10, 000 tests ( .01%) in a reported 170, 000 exercise

tests administered to patients in clinical laboratories,

the subject's interpretation of a stressful condition may

result in a less than maximal effort. • Preceeding the use of direct measurements of vo2 max

for assessing physical performance, tests were employed to • measure parameters suspected to be closely related to V02 max.

Shephard (1969) indicated that most indirect measurements used • to predict V02 max were based on some measure of heart rate

response asstiming that: ( l) a linear relationship existed

between heart rate and oxygen uptake over a range of work

loads from 0-90.% of the ma:x:imum oxygen consumption and

(2) there existed a constant maximum heart rate for a given

population •

.Among the first investigators to use heart rate as an

indicator of physical fitness was Tuttle ( 1931). He

11

developed the Tuttle Pulse-Ratio test which relied upon

measurements of heart rate following bench stepping to • predict VO 2 max~·

• The most popular criticism of predicting vo2 max from

heart rate responses involved the lack of control

physiologists had over such variables as age, altitude,

anxiety; fitness level and environmental temperature which

influenced heart rate. Devries and Klafo ( 1965) and

DeVries (1968) investigated and found that the Progressive

Pul.se-Ratio test and the Harvard Step test, representing • additional. tests of predicting vo2 max, produced errors

of ± 1 J .'7% and ± 12. 5% respectively, for predicting vo2 max.

Fu.rthurmore, .Ast rand and Roda.h.l ( 1970) indicated that when

these variables were not properly controlled9' errors were • made in V~ max predictions.

Consequently, tests were devised to measure

perform.a.nee capacity and relate this measure to circulo-

respiratory function. At present, performance capacity is

generally assessed through measurements of.physical working

capacity {PWC).- Sjostrand (1947), Wahlund (1948) and

Astra.nd and Rhyming (1954) were among the first to introduce

the methods for determining PWC. They found that a maximum

work output could be predicted f:rom PWC based on the linear

interpolation of heart rate.- Therefore, the PWc170 test

(Sjostrand, 1947; and Wahlund, 1948) identified the work

12

·capacity of an individual at an estimated level of maximum

· cardiovascular efficiency (170 bts/min). This predetermined

endpoint of 170 bts/min has been generally accepted as the

level abe>ve which no significant increase 1n·heart stroke

volume occurs (Devries;' 1968)• . .Astrand and Rhyming (1954)

went one step furthur and were responsible for utilizing PWC

to estimate "O'o 2 max;' They developed a nomogram predicting • vo 2 max values based on heart rate, workload, age and sex

from PWC. GeneraJ.11• the target heart rate in their testing

procedure was 80•90" of the age ad.justed, predicted maximal

heart rate. De'Vries ( 1968) found that a correlation of

r=.88,; P~· 05 existed between 1o2 max predicted trom PWC and

actual measurements of to 2 max~·

However, additional. oorrelationaJ. studies indicated

significant discrepancies between estimated and measured . . values of VO 2 max• In one of these studies Teraslinna,

Ismail and MacLeod (1966) found a correlation coefficient .. · of r=~'69 ,' p ~ .:05 between estimated vo2 max values predicted

from heart rate workload. relationships in the PWC test • and measured vo2 max 'Values. Furthurmore,· Davis (1968)

concluded that when measurements ot oxygen uptake required

accuracies within +15% of the true value, then direct

measurements should be taken. • The main restriction associated with vo2 max

predictions from PWC parameters may be related to the

13

differences in the exertional chara.eteristics of the tests,

i.e. nonsteady-state versus steady-state exercise.

Measurements taken during PWC testing reflected stability or

asymptotic patterns that indicated physiological adjustments

to a given work output; whereas, nonsteady-state exercise • associated with vo2 max required physiological parameters

to show asymptotic patterns only as a result of maximal

output. In addition, physiological parameters at FWC

represented functional measurements assumed to be most

efficient, as related to heart rate; whereas, vo2 max re-

presented the maximal value of physiological parameters.

In addition to the previous types of tests, there also

exists a battery of field tests which purport to measure

circulorespiratory endurance. .Among these tests (such as the

Army Air Force Physical Fitness Test, 1946; GaJ.laghen and

Brouha Test•· 1943 and Cooper•s 12 min walk/run test, 1963),

the type most commonly used related a distance walked/run

during a specified time to 'O'o2 max (Balke, 1963 and Cooper, 1969). The primary advantage of these tests was their

simplicity and utility in evaluating large numbers of

subjects in a short period of time. However, these praot1oal

tests were very similar to those using other indirect

predictions of maximal performance and capacity. Hence, the • previous limitations of indirect measurement of V02 max

were also applicable for the field tests.

14

It appears that previous tests relied heavily on the

use of aerobic parameters to measure circulorespiratory

endurance and performance capacity. This may serve as a

limitation, in that exercise was not an exclusive function

of aerobic processes. Conditions existed (initiation of

exercise and strenuous exercise) in which aerobic processes

were not adequate for the exercise and thus required the

assistance of an.aerobic processes. For this reason, it is

important that both processes be examined in relation to

their use as measures of physical performance.

THE INTERPLAY OF AEROBIC AND AN.AEROBIC MEr.ABOLISM

The distinguishing factor that differentiates aerobic

metabolism from anaerobic metabolism is the availability of

oxygen at the cellular level. In the case of aerobic

metabolism, the oxygen available at the cell is used as

the final electron acceptor in the electron transport chain;

whereas, the final electron acceptor for anaerobic metabolism

is some molecul:e other than O:J:Ygen. Therefore, the breakdown

of glucose to provide energy (KrP) for muscular work can

follow two separate pathways, depending on the availability

of oxygen. If adequate supplies of oxygen exist; the

degradation of glucose to form energy fo1lows a pathway

whereby electrons donated from the oxidation of

glyceraldehyde-3-phosphate are accepted by NAD to form NADH;

15

NADH oxidizes to transfer electrons with the assistance of

shuttle reactions, to the mitochondria and v1a the electron

transport chain to the oxygen molecules (Miller, 1968).

A.strand and Roda.hl (1970) suggested that this pathway was

used primarily when the exercise intensity was below heavy • levels (~ 60-70% vo2 max).

IUring anaerobic cond1t1ons adequate stores of oxygen

are not available tc:> accept electrons; therefore; the

oxidation of NA.DH must follow an alternate pathway. This

pathway involves the acceptance of electrons by pyruvic

acid to form lactic acid. Consequently, any accumulation

of lactic acid in the circulatory system (blood) reflects

increasing levels of glycolys1s, an anae~obic process (Miller,

1968). This pathway is generally associated with exercise

intensity levels higher than that ot heavy work { ~ 60-70% • vo2 max).

The examination of the interplay of aerobic and

an.aerobic metabolism identifies two separate and distinct

parameters (oxygen and lactic acid) for differentiating

metabolic activity associated with physical performance.

The use of oxygen in evaluating physical performance has

been widely accepted by exercise physiologists. However, the

identification of lactic acid as a parameter of anaerobic

metabolism is suggestive of alternate methods of examining

cireulorespiratory endurance and performance capacity.

16

MEl'ABOLIC .AND PULMONARY GAS EXCHANGE CHARAarERISTICS .ASSOCIATED WITH

THE .ANAEROBIC THRESHOLD

Hill, Long and Lupton (1924) reported that the respira-

tory g~ exchange ratio (R) was_ an indicator of differing

levels of lactic acid production. They indicated that

changes in blood lactic acid concentrations had direct effects

on R (R=VCO~vo 2) and particularly the amount of co 2 expired

at the mouth. Therefore, if lactic acid in the body did

not increase R remained lower. In contrast, when an

aocumulat ion of lactic acid occurred in the blood an • increase in R was observed, accompanied by a rise in vco 2 •

• This increase in VC0 2, described by Hill,· Long and

Lupton (1924), can be related to the effect of lactic acid

on the buffering systems of the body•' When energy

requirements can be met by aerobic reactions and a steady-

state maintained, the co2 produced diffuses from the active

tissue into circulating red blood cells. In the erythrocytes,

dissolved co2 combined with water (H2o) to form carbonic

acid (H2co3) with the assistance of a catalytic enzyme, . +

carbonic anhya:ase. The H2co3 ionized into H and Hco3 such that HCO 3 can be diffused across the cell membrane and

transported in the plasma. .Astrand and Rhyming ( 1970)

indicated that approximately 70% of. the Hco3-was transported + in the plasma. The remaining free H ions were bu~fered in

the erythrocytes by hemoglobin (Hb) after o2 and Hb dissociated

17

and a weak acid (H+Hb) was formed in the venous blood

leaving the active tissue. For this reason, the final

pathways for co2 transport at ion were: ( 1 ) Hco3 - in the

plasma,' ( 2) co2 combined with Rb to form carbminohemoglobin,

and (3) co2 dissolved in the erythrocytes.

When e::x:ereise conditions are strenuous~· lactic acid

is produced in the tissue and diffuses into the plasma where + it initiates att increase in the H ion concentration,

thereby increasing the formation of a weak acid from Hco3-+ . -(H + Hco3 from Hico3 ) •1 However, ~coj dissociates into

~O + C02 causing an increase in :free co2 and a decrease in

blood pH (Astrand and Rodahl, 1970). This increase in :free

co2 and decreaae in blood pH levels stimulates the respiratory

center(s) ~o increase ventilation (Astrand and Rodahl, 1970);

therefore1': the increased ventilation reflects the effects

of increased levels of co2 1n circulating fluids, causing

a corresponding increase in the gas exchange ratio (R) at • the mouth in the form of an increased vco2• This increase

-~~ • 1n vco2 is related to the displacement of co2 buffering

arising from the need to buffer lactic acid which has

accumulated in the blood during anaerobic. processes. Hence, • R and vco2 have recently been used to identify changes in

lactic acid production as related to anaerobic metabolism

(Wasserman et al, 1973)• Margaria, Edwards and Dill (1933) were first to suggest

18

a relationship between lactic acid mechanisms and the

anaerobic metabolic state. They found that the appearance

of excess lactic acid in the blood did not occur until work

rates exceeded two-thirds of the maximum metabolic rate;

a.~d above this level 'or metabolism, they observed that lactic

acid increased at a rate of 7.0 mg/liter for each 1 liter

increment of o2 debt. They concluded that the mechanism of

lactic acid production did not play an important part in

muscular contraction except under conditions of intense

exercise.

This relationship was supported by Issekutz and

Rodahl (1961) when they suggested that increases in R

during exercise may be attributed to the imbalance between -the formation and elimination of lactic acid with respect

to reactions with the bicarbonate system. They compared

excess (nonmetabolic) co2 with blood lactate levels during

the first 4-5 minutes of exercise to define R. They

identified excess co 2 to be: (1) co2 produced by non-

metabolic sources and (2) the total co2 minus 0.75 X o2 ,

where 0.75 represents a close approximation of the actual

metabolic R. Using this assumed metabolic R, a correlation

coefficient of r=.92, p ~. 05 was found between A lactate

and excess co2 , based on 102 measurements. Therefore, they

concluded that the excess co2 divided by o2 uptake, called

A R, seemed to represent the percentual participation of

19

anaerobic glycolysis during exercise.

Furthurmore, Issekutz and Rodahl (1961) suggested that

since lactate concentrations were higher in active tissue

than in thELblood and since the diffusion rate of co2 was

presumably more rapid than lactic acid, then it appeared

likely that excess C02 followed anaerobic metabolism more

closely than blood lactic acid levels. Their conclusions

were based on investigations indicating that: ( 1) R varied

with changes in work intensity and (2) the relative increase

in C02 compared to o:x:ygen uptake could not be attributed

to hyperventilation as evidenced by the absences of a

decrease in alveolar and arterial pco 2 during exercise.

Naimark, Wa.sserm.an and Mcilroy (1964) were first to

use techniques of rapid breath-by-breath gas analysis to

review the relationship between the increase in R during

exercise and metabolic acidosis. Their findings were

similar to those of Issekutz and Rodahl ( 1961), suggesting

.that a relationship existed between increases in R during

short exercise periods (3-6 min) and metabolic acidosis,

as indicated by increases in blood. lactate concentrations.

In addition, they concluded that the close correspondence

between R and ~lactate suggested that the increase in R

and the decrease in plasma bicarbonate were due to· acid

production resulting from glycolysis rather than from

hyperventilation"' They also indicated that ~R did not

20

follow a simple linear relationship with respect to changes

in the plasma bicarbonate~'

Wasserman;' van Kessel and Burton ( 1967) used rapid

breath-by-breath analysis to look at the interaction of

physiological mechanisms during exercise. From their

research a relationship was suggested between minute • ventilation (Ve) and the onset of metabolic acidosis. It

was shown that under conditions of heavy exercise, the

increase in Ve was disproportionately greater than the • • rise in either vo2 or vco2 , thus indicating metabolic

acidosis; as described by Comroe (1965)• This disproportion-

ate change was the result of compensation for metabolic

acidosis by the respiratory system. For this reason,

increased ventilation represented the :f"u.nction of excess co2 • • which reflected the relationship between Ve and vco2 and not

• • • vo2; This rel at ions hip between Ve and vco2 was found to be

less variable and more linear than that between measures of • • • Ve and vo2 ~· This implied that Ve was more closely

associated with co2 than o2 metabolism.

Whipp and Wasserman (1972) used breath-by-breath

anaJ.ysis to determine oxygen uptake kinetics during • nonstead.y-state exercise.· Their study indicated that vo2

was dependent on the exercise intensity and the physical

fitness level of each subject. Also, it was found that if • the vo2 difference between the 3rd and 6th minute of exercise

21

was zero the work was aerobic. However, if the difference

was a finite value then anaerobic contributions were rising.

This implied that At could be determined directly by

measuring vo2 at two different intervals of graded exercise.

Wasserman et al (1973) introduced an additional criteria

for detecting the onset of metabolic acidosis (AT). They

found that the simultaneous measurement of end-tidal O 2 and

end-tidal co2 could be used to indicate the AT by deter-

mining the point at which there was an increase in PETOz

without a corresponding decrease in PEI'co2• In spite of

this determination, they suggested that the easiest technique • for detecting Kr would be to measure Ve during an incremental

exercise test and look for the point at which the Ve exercise •

intensity curve becomes nonlinear; Ve being closely related • to changes in VC02 thus reflecting metabolic acidosis as

described by Wasserman, Van Kessel and Burton (1967).

SU11NARY

In their quest to accurately define and measure

physical fitness, exercise physiologists have developed

many tests purporting to identify this index of performance.

Literature has shown that the most accurate and reliable

method of assessing function has been direct measurements

of V02 max as described b~ .Astrand (1952) and Taylor, Buskirk

and Henschel ( 1955). Predeeding direct measurements were

22

. indirect measures of V02 max used to predict performance.

The use of both types of measures has been extensive in

the review of function and performance. However,

physiological and psychological factors associated with • direct and indirect measurement of V02 max were found to

limit the accuracy of the measure.

As refinements were made in assessing performance,

researchers turned to the study of components of performance;

such as oxygen debt, lactic acid production and aerobic/

anaerobic processes. Recently, investigators have been

interested in the aerobic and anaerobic processes of

performance and how they relate to fitness and conditioning.

Therefore, studies (Hill, Long and Lupton, 1924; Margaria,

Edwards and Dill, 1933; Issekutz and Rodahl, 1961; Naimark,

Wasserman and Mcilroy, 1964; and Wasserman, Van Kessel and

Burton, 1967) of the interplay of aerobic/anaerobic

metabolism were used to examine the ability of the exercis'er

to direct the utilization of fuel through either of two

metabolic pathways depending on the availability of oxygen

resources.

From the progressive understanding of metabolic

function, researchers (Whipp and Wasserman, 1972 and

Wasserman et al, 1973) have identified the concept of AT;

describing the point of aerobic/anaerobic exchange. This

concept added new dimension for the examination of function

23

and performance. However, measurements of Nr were complex

until Wasserman et al (1973) suggested that the Nr could

be predicted by the point of exercise associated with

nonlinear changes in the Ve exercise intensity curve.

J

Chapter J

METHODOLOGY

The organization of subjects, procedures, instrumenta-

tion, test design and data analysis was included to establish

the format for the development of relations of anaerobic

threshold, circulorespiratory endurance and performance

capacity.

,SUBJECI'S

Ten male students, 1a ... 25 years of age, at Virginia

Polytechnic Institute and State University enrolled in

physical education classes volunteered to be subjects for

this study. Only those who were physically active, as

defined by regular participation (twice/week) in an exercise

eliciting a sweating response or heart rate response of at

least 120 bts/min, became subjects. Physically active

subjects were selected to minimize the chance that latter

trials would be influenced by training effect.s ·from exercise

in previous trials.

Each subject enrolled in the study was informed,

through written explanations and individual discussion, of

potential hazards associated with exercise testing. In

addition, subjects were asked to sign an informed consent

before testing began.

24

25

PROCEDURES

A preliminary examination, the protocol of the testing

series and trial parameters' are discussed to establish

the basic procedures for this study.

Preliminary

Prior to experimental testing (week 1), each subject

reported to the Human Performance Laboratory in the War

Memorial Gymnasium for familiarization of test equipment

and procedures. During this visit the following anthropo-

metric measurements were taken: height (cm), weight (Kg)

and skinfolds (mm) which included the following sites;

front thigh, subsc~ular, triceps and iliac. A summary .. of these descriptive measures can be found in Table 1.

For individual descriptive data refer to Appendix A.

In addition, each subject practiced a wall~/jog

exercise on the Quinton 24-72 tread.mill. As subjects

adapted to exercise on the treadmill, speed and grade

were changed to simulate conditions of graded exercise

trials. Safety precautions for the use of the treadmill

were discussed before and after the exercise. After the

treadmill exercise, each subject was fitted with the

breathing valves and hoses to be used for gas sampling

during actual experimental trials. In addition, subjects

participated in a demonstration of procedures to be used

26

Table 1

Summary of Descriptive Measures

Measures :x §..:12. n

Age (yrs) 22.4 1.1 10

Height (cm) 179.6 7.7 10

Weight (Kg) 72.6 4.6 10

Skinfolds (mm)

Front Thigh 13.6 6.4 10

Subscapular 10.a 2.0 10

Triceps 11.2 4.0 10

Iliac Crest 10.6 5.5 10

27

for monitoring heart response during the exercise trials.

Protocol for the Experimental Testing Series

Upon completion of the preliminary tests, subjects

were randomly assigned to experimental trials: ( 1) PWC 170,

(2) ff£1, (3) M2 and (4) 1.5 mi run/V02 max. The random

order of experimental trials can be found in Appendix B.

The PWC 170 represents a physical working capacity trial

with a terminal target heart rate of 170 bts/min. The

symbols .AT 1 and N£ 2 represent repeated trials of Kr. The

1.5 mi run/vo 2 max identifies the field trial for the

1. 5 mi ru.."1 followed by a circulorespiratory endurance trial • of V02 max. .All tests were conducted within a three week

period.

Parameters

Functional capacities were evaluated using circulo-

respiratory measurements taken during the PWc170 , AT 1 , l'Ir 2 , • and V02 max trials. Circulorespiratory measurements

consisted of: (1) heart rate (bts/min), (2) oxygen

uptake ( V02, L/min), ( 3) minute ventilation (Ve, L/min)

and (4) estimated end-tidal values of oxygen and carbon

dioxide (PE:r02 and PErco2 , respectively). Exercise level

(MET) was used as a measure of performance. Performance

time ( sec) and immediate post -ex ere is e heart rate were the

parameters measured during the 1 • .5 mi run trial.

28

INSTRUMENT AT ION

All exercise trials were performed on a Quinton 24-72

motor driven treadm.111 equipped with a Programmed Exercise

Control (Model 643). Exercise levels for each experimental

trial were programmed using this unit, allowing for the ' production of constant changes in speed and grade. Electrodes

were mounted on the chest of each subject ( CM5 lead) for

measuring heart rate via the electrocardiogram. Electro-

cardiograms were recorded during conditions of: · rest ( 5 min),

exercise ( 0-25 min), and recovery (at least 5 min); using

. the Quinton ECG Monitoring System (Model 621B). The ECG

recordings were taken during the final 10 sec of every

minute in each trial. Respiratory gas exchange measurements,

for all trials requiring it, were collected and analysed

using the Parkinson-Cowan CD-4 spiromet er (Ve), the

Beckman LB-2 carbon dioxide analyzer (PErco2 ) and the

Beckman 0!1-11 oxygen analyzer (PEro2 ) •

For the .P££ trials, in addition to the equipment used

above, a Honeywell Oscillographic Recorder (Model 1858) was

used to display an analog recording of PEI'C02 and PEI'o2

values produced from outputs of the Beckman LB-2 and OM-11

analyzers, respectively. All instruments were calibrated

before each trial.

29

TEST DESIGN

Test-retest ( .AT1 and .AT2) methods were used to establish

the reliability of .AT. In addition. .AT was compared to

other trials (PWC:i.70 and the 1.5 mi run/vo2 max) to deter-

mine the validity of its. use as a measure of circulo-

respiratory endurance and/or performance capacity.

Protocol for Trials

PWc170 • Subjects performed a test of incremental

workloads on the treadmill consisting of 3 minute stages.

The stages are presented, in Table 2. Subjects progressed

through each stage until a heart rate of 170 bts/min was

obtained and maintained for at least 2 min of the 3 min

stage; at. which time the trial was terminated.

An open circuit system was used to collect respiratory

gas exchange data during this trial. Gas sampling was not '

initiated until the subject's heart rate exceeded lJO bts/min.

Sampling continued from this point until the endpoint of

exercise. Two pieces of flexible plastic tubing (I.D.=liin)

were connected, one to the inspired and the other to the

expired side of a Daniel's breathing valve. The plastic

tubing on the inspired side was connected to the Pa.rkinson-

Cowan meter, while on the expired side the tubing joined

with a J.5 L mixing chamber. Gas samples were extracted

from the mixing chamber with an electric diaphram pump

30

Table 2

Incremental Workload Stages for PWC170

Stages Speed (mph) Grade (%)

warm-up 3.5 No grade

1 4.5 NO grade

2 6.o 2.5 3 7.0 2.5 4 7.0 5.0 5 8.0 5.0 6 8.0 7.5 7 9.0 7.5 8 9.0 10.0

Cool-down 3.5 No grade

Time/stage = 3 min

31

and stored in 2 L anesthesia bags via a Wilmore 3-way valve.

The anesthesia bags and the Wilmore 3-way valve were used

to sequentially collect, a.11alyse and exhaust gas samples

in 30 sec intervals for expired o2 and co2 content.

1.5 mi run/V02 max. The 1.5 mi run trial was preceeded

by a warm-up stage ( 3.5 mph, no grade) of 3 min. The trial

was performed on the treadmill with no grade and a self-

determined speed perceived by the subject to be the maximum

rate for achieving the 1.5 mi distance in the shortest time.

The speed was increased and decreased throughout the test

according to each subject's expectation of a maximal

performance. Heart rate and performance time were recorded

for each subject. Heart rates were recorded via ECG during

the last 10 sec of each minute throughout exercise. Oxygen

consumption values were predicted from 1.5 mi run perform-

ance times using linear interpolation of tabled norms

developed by Cooper ( 1969). These norms are presented in

Appendix c. • The 1. 5 mi run preceeded the V02 max trial. The

interval between trials was dependent on the time required

for the recovery heart rate to return to the resting level

which had been recorded prior to the 1.5 mi run.

For the V02 max trial, subjects performed the incremen-

tal workload tread.mill run described for the PWC170 trial,

except stages were decreased to 2 min and the trial was not

32

terminated until the subjects declined to continue (Note:

if subjects reached the 9th workload, this load remained

constant until exhaustion.). Respiratory gas exchange data

was collected via the same open circuit system described

for the Pwc 170 trial; however, samples were collected and

analysed beginning the first 30 sec of exercise and every

·JO sec thereafter. Heart rate was recorded as in other trials.

xr 1 and u:r 2• Subjects performed a run on the treadmill

of 1 min incremental exercise loads until they declined to

continue. The increments consisted of a warm-up ( 6 mph, no

grade for 2 min) followed by stages with speed held constant

(7.5 mph) and with grade increased in 1% increments, thereby

co,nforming to the Wasserman et al ( 1973) hypothsis that

small increases in work outputs are required to produce

identifiable N!s. The incremental increases in work outputs

for this study were set for approximately .5 MEI'/stage.

A modified open circuit system was employed to collect

respiratory gas exchange data. On the inspired side of the

breathing system, tubing was connected to the Parkinson-

Cowan met er and the Dani el' s breathing valve in the met hod

described for the Pwc170 trial. On the expired side, the

inlet tubing ( 1/16 in) to the Beckman analyzers was directly

connected to the Daniel rs breathing valve. This connection

was made at the midpoint between the inspired and expired

d1aphrams of the valve and directly opposite the breathing

33

oriface. This modification allowed the Beclmtan analyzers

to sample gas for o2 and co 2 concentrations with each

breath. Breath-by-breath changes in PEro2 and PETco2 were

recorded on the Honeywell Oscillographic Recorder (Model 1858}.

The breath•by-breath responses were recorded and displayed

in the middle 10 sec of the 30 sec interval; i.e., at

10-20 sec and at 40-50 sec within each minute. This allowed

measurements of te to be paired with PEI'o2 and PEI'C02 values • for calculations of V02. Heart rate was monitored as

described for other trials.

Det erminat io.n of AT

The PE for this study was determined by the point of . .

the Ve exercise intensity curve expressing nonlinearity as

described by Wasserman et al (1973). • Ve was plotted in . .

conjunction with exercise levels pro.ducing Ve exercise

intensity curves which expressed the linearity of the

function. This relationship and technique are presented

in Figure 1. The Ve exercise intensity curves established

for each subject showed differing rates of change with

increases in workloads. This variability necessitated the

administration of a curve smoothing procedure. Therefore, ' • each Ve exercise intensity curve for each subject 1 s Pa trial

was pl9tted against a corresponding smoothed curve derived

by linear regression techniques. This technique provided a

more distinct presentation of the two curves enabling a

34

110

100 K •

90

Vie 80 (L/min)

2 3 4 5 6 7 8 9 10 11

WORKLOADS

FIGURE I. Anaerobic Threshold Determination

From \1'e E . I t "t v xerc1se n ens1 y Curves, Using

Linear Regression for . Loads A-D. The

Assumed Linear Path of the ~e Response

was Predicted for Identifying Nonlinear

Changes in ~e with Furthur Increases

Graded Exercise Levels.

3.5

high degree of discrimination for establishing the speed-

grade level at which the .PI1 occurred; also reducing error

associated with subjective analysis of curve patterns • • Appendix D reviews the procedure for calculating V02 from

breath-by-breath techniques used in this study.

DNrA ANALYSIS

Pearson product-moment correlation coefficients were

calculated to provide indices of reliability and validity

for AT; relative to how variations in this characteristic

might be associated with the patterns for other measures

of exercise performance. In addition, the test of means

paired difference was used to describe the difference

between mean responses for trial measures. Coefficients

of correlation r=.80 with p ~. 01 were considered to be

expressions of reliability and validity for AT parameters.

In the comparison of parameter means, levels of significance

were set at p s_. 01.

Chapter 4

RESULTS

The reliability and validity of .AT as an index of

c1rculorespiratory endurance and performance capacity was

established using correlationa.l comparisons. In addition,

the significance of parameter mean relationships was

examined by tests of means paired differences.

Kr RELIABILITY

There exist two areas for which the reliability of AT

was established: ( l) the reliability of the AT prediction

technique and (2) the reliability of parameters associated

with AT. The reliability of predicting .AT using nonlinear • changes in the Ve exercise intensity curve was described

by a coefficient of correlation comparing exercise intensities

at Pf!. This comparison produced a significant coefficient

of correlation {r=.94). The scatter plot for this comparison

can be found in Figure 2.

Reliability measurements were also established for • parameters associated with .AT. It was found that V02 and

• Ve measures produced significant coefficients of correlation

(r=.94 and r=.82, respectively); while the comparison of

heart rate responses failed to produce a similar result. • • The similarity of repeated measures for VOz and Ve can

36

15

13

Exercise Intensity

11 @ AT2

(ME TS ) 9

7

•

7

37

• •

..

... • •

•

r = .94

r2= .8 8

9 11 13 15

Exercise In tensity @ A T1 ( M E TS)

Figure 2. Line of Regression for Scatter

Plot of Exercise Intensity Measurements

of AT, Expressing Reliability.

38

be seen in Figure 3 and Figure 4, respectively. The heart

rate comparison can be reviewed in Figure 5. Using the test of means paired differences revealed

no significant difference between parameter means (Table J} describing circulorespiratory function at Pf!. This finding

• • was true for all parameters (VOz, Ve and heart rate). A

summary of these comparisons is presented in Table 3.

lf£ V .ALIDITY

la validity was examined by comparisons of functional

and performance parameters at ll! to corresponding parameters

of recognized tests of circulorespiratory endurance ('O'o2 max

and .Astrand•s prediction of V02 max) and performance capacity

(PWC170 and the 1.5 mi run) •

• ll! versus V02 max • • The comparison of ll! parameters (vo2 , Ve and heart

• rate) to corresponding parameters of vo2 max produced vary-

ing degrees of correlation. A summary of these correlations

can be found in Table 5. Results indicated no significant

coefficients of correlation existed for expressing the • validity of P/£ as a measure of vo 2 ma::x: •

.AJ.though differences between parameter means (Table 4 )

ranged from 8-22%, tests of means paired differences showed

a significant difference between means for all parameters• • comparisons of AT and V02 max. These results are presented

60

50

vo2 @ AT 40

{ml/kg min)

30

2

'39

•

20 30

' • • •

40

~02 @ AT1

(ml/kg - min)

• • • •

50

r = .94 r2 =.88

60

FIGURE 3. Line of Regression for Scatter

Plot of Oxygen Uptake Measurements at

AT, Expressing Reliability.

90

80

ve @ AT2 70 (L /min)

60

50

40

.

•

50 60

•

• ••

70

Ve @ AT1

(L/min)

,,, •

80

•

r = .82 r2 = .67

90

•

FIGURE 4. Line of Regression for Scatter

Plot of Minute Ventilation Measure men ts

at AT 1 Expressing Reliability.

HR@ AT2 (bts/min)

180

170

160

41

•

10

HR@ AT1

(bts/min)

•

r = .40 2 r =.16

180

FIGURE 5. line of Regression for Scatter

Plot of Heart Rate Measurements at A T,

Expressing Reliability.

42

Table J

Summary of Statistical Measures for Repeated AT Trials

Parameters AT1 AT2

• (L/min) V02

x 42.9 42.4

~ a.5 7.3 n 10.0 10.0

• Ve (L/min) - 74.4 78.3 x

~ 14.5 17.6 n 10.0 10.0

HR (bts/min) - 172.2 173.2 .x

S.D. 4.4 4.1 -n 10.0 10.0

4J

Table 4 Summary of Statistical. Measures for

Funct iona.l. and Performance Trials

Function Performance

(a) Parameters Avg • .AT 'O'o 2 max .Ast. Pred. PWc170 1.5 mi run

vo2 (L/min) -:x:

s.n. -n

Ve (L/min) -:x: '

~· n

HR (bts/m1n) -x

~· n

42."6

7.9 10.0

76.3 16.0

10.0

50.'0*

7.2 10.0

97·3* 12.6

10.0

172.7 188.4*

4.2

10.-0 10.0

48.5*

8.0

lO•·O

40.'4

6.·2

10.0

74.4 9.4

10.0

44.1

9.8 10.0

170.0 184.2* 172~6

o.o 11.2 11.4

10.0 10.0 10.0 (b) (c)

* Represents a significant difference between means when compared to reference measure of Avg. Kr ; using the test of means paired differences with t? tJ.250 for p ~ .01, df=9·

(a) Based on Average of .AT 1 and xr2 trials ( b) Based on t e:rminal heare rate measurements

·(c) Based on average heart rate for trial duration * Parameter not measured

Kr vs

Table 5

Coefficients of Validity for Jtr Comparisons

Parameters

• • Trials of VOz (L/min) Ve (L/m1n) HB. (bts/min)

• VOz max .69 .53 Astrand•s Pred.

ot to2 max .76 * PWC170 .80* .38 1.5 mi ~ .82* *

* Coef':ficient of correlation s1gn1:ficant at p ~. 01

* Not recorded

(a) Based on terminal heart rate

(b) Based on average heart rate for trial duration

.41

+ -.32

.17/ .30 (a) (b)

45

1n Table 4.

·.Nr versus Astrand•s Prediction of vo2 max

• Astrand• s prediction of vo2 max was the second triB.l

used to identify the validity ot Kr as an index Of :functional • measurement. (Note: Astrand•s prediction of V02 max was

• compared to measured V02 max to ascertain its validity as a

:functional m.easure. A coefficient of correlation, r=.80,

was found expressing validity.) • Using V02 measurements, the results of the comparison . .

of AT and Astrand•s prediction of V02 max failed to produce

a significant coefficient of correlation (Table .5). This

lack of correlation corresponded to previous .·comparisons of

Ill to measurements of functional capacity. Furthurmore. . .

the comparison of means for V02 between trials produced a

significant difference ('!'able 4)

AT versus PWC1zo The review of functional prediction from performance

• measurements revealed that the comparison of V02 measures

between Kr and PWC170 produced a significant coefficient

of correlation.; whereas, no significant expression of .. validity was found for remaining parameters of Ve and

heart rate. A StimmSJ:'Y of these findings may be reviewed

in Table 5. The comparison of means between parameters of AT and

PWC17o indicated no significant difference using tests of

means paired differences. Theeecomparisons are described

in Table 4.

AT versus . 1. 5 mi run

The 1.5 mi run represented a field trial expressing

the subjects' ability to predict and maintain a performance

level for maximizing endurance performance measures. The

comparison between AT and the 1.5 mi run was based on • predicted vo 2 and heart rate parameters; where comparisons

• of predicted vo 2 and heart rate from the 1.5 mi run and • • measured VO 2 and heart rate of the VO 2 max produced

coefficients of correlation (r=.68 and r=.10, respectively). . . The comparison of V02 between AT and the 1.5 mi run produced

a Significant coefficient of correlation (Table5) •. This

expression of Kr vaJ.idity was not supported by comparisons

of heart rate responses, which produced a low correlation.

A review of mean differences (Table 4) indicated • several relationships. The comparison of V02 means revealed

no significant difference. However, a difference between

means was found for the comparison of heart rate at ff! to

terminal heart rate at the 1.5 mi run. .As this measure did

not represent a function of the 1.5 mi run duration, an

average trial heart rate was obtained; whose mean when

compared to that of K! produced no significant difference

using the test of means paired differences (Table 4).

Chapter 5

DISCUSSION

Furthur understanding of the relationships between

anaerobic threshold, circulorespiratory endurance and

performance capacity can be developed through the evaluation

of factors contributing to AT reliability and validity;

from which basic conclusions can be formulated. In addition,

the examination of these contributing factors may introduce

implications for the use of AT.

Using the premise of Wasserman. et al (1973) that a

nonlinear change in the relationship between Ve and exercise

intensity curves predicted X!, AT and its associate parameters

were examined for expressions of reliability and validity

described by coefficients of correlation and the similarity

of parameter mean scores described by tests of mean paired

differences.

AT Reliability

Test results indicate that AT can be predicted from • the determination of nonlinear responses in the Ve-exercise

intensity curve. This can be substantiated by the high

coefficient of correlation (r=.94) produced for the

comparison of exercise intensities associated with predicted Nrs.

This finding establishes the reliability of the Jlf measurement

47

48

technique, as 88% of the predicted .Krs can be explained by

the linear relationship between exercise intensity measure-• ments associated with nonlinear Ve responses.

This h1gh coefficient of correlation may be the result

of the simultaneous influence of: ( 1) the consistancy with

which the exchange in aerobic/anaerobic processes follow • exercise demand and ( 2) the validity of nonporport ional Ve

response representing metabolic acidosis. This explanation

is based on the premise that the exchange from aerobic to

anaerobic processes occurs at a constant exercise demand

controlled by the physiological limitations imposed on the

aerobic pathways when exercise requirements are heavy; and

that this limitation of aerobic processes coincides with

the onset of metabolic acidosis, which can be identified by • nonlinear Ve responses described by Wasserman et al (1967).

In addition to establishing the reliability of Kr,

coefficients of correlation were used to define the • • reliability of physiological parameters (Ve, V02 and heart

rate) associated with Kr. In reviewing these parameter )

relationships, significant coefficients of correlation

were described for respiratory indices, while the comparison

of heart rate responses failed to produce a significant

correlation. • The examination of the Ve parameter for the K! trials

in this study revealed a relatively high coefficient of

correlation (r=.82) and no significant difference between

• means expressing the reliability of Ve at 1f1. This finding • should be expected as changes in Ve responses represent the

primary measure used to assess the reliability of the Kr

prediction. Therefore, its reliability may be explained

by the same factors previously discussed for Kr determin-

ation. However, it might be noticed that a difference

exists between coefficients of correlation for the reliability • of N£ and Ve at Kr. This difference may be attributed to

• variability of the Ve parameter during nonsteady-state

conditions associated with aerobic conditions.

A high coefficient of correlation (r=.94) and no

significant difference between means was also found for the • comparison of vo2 responses at J&!r. This finding may be· . - . directly related to Ve reliability as V02 is a function of

• Ve times true oxygen uptake.. .An additional explanation may • be that vo2 at Kr represents a. constant measure of optimum

aerobic processes preceeding the onset of anaerobic conditions.

The comparison of heart rates at Kr was the only measure

which did not produce a significant coefficient of correla-

tion. .As there is no significant difference between

parameter means, this low correlation probably reflects

the variability of heart rate responses caused by nonsteady-

state exercise associated with the AT trial; where effects

of fatigue, temperature and psychological stimuli affect • • heart rate but have minimal affects on Ve and V02. This

50

would partially explain the differences in coefficients of

correlation.

From the examination of results and their contributing

factors, there appears to be evidence to suggest that Kf

is a reliable measure which produces reliable respiratory

measurements.

Nr Validity

In addition to establishing test reliability, the

results of this study were used to simultaneously examine

Kr validity with respect to reference measures associated

with functional capacity and endurance performance testing.

In examining Kr as an indicator of functional capacity, • • the V02 max and Astrand 1 s prediction of V02 max were

employed. Astrand•s (1952) early investigations established • the v~lidity of V02 max as a measure of capacity. Similari-

• ly, the use of Astrand•s prediction of V02 max as a measure

of circulorespiratory capacity was supported by Astrand and

Rodahl (1970) and the findings of this study (Chapter 4).

Therefore, similarities between indices of Kr and functional

tests are assumed to describe the validity of Nr as a mea-

sure of circulorespiratory function •

• Kr versus V02 max. The review of test results for Kf

validity shows that no significant coefficients of correla-

tion are produced by the comparison of parameters {V02, te

.51

and heart rate) between AT and V02 max. This suggests that

AT parameters are not valid indicators of circulorespiratory

capacity. This finding may be attributed to variab1l.1ty

associated with comparisons of linear and nonlinear parameter

responses describing dissimilar function at different exercise

intensities.

Furthurmore, the significant difference between means

for trials 1 parameters suppo~s the finding that dissimilar . .

function exists between AT and V02 max. Mean results show

that at least a 1.5% difference exists between vo2 require-• ments for AT and V02 max. As M was produced at discernably

lower exercise intensities, results show that heart rate

responses were lower; but not in porportion to that found • for V02• Instead, heart rate at AT reflected an approximate

8% decrease when compared to heart rates at vo2 max. It is

suspected that this smaller difference may be the result of

asymptotic effects produced by heart rate responses approach-

ing maximal endpoints. This relationship is described in

Figure 6. • Mean scores for Ve at Hf were al.so lower ( 22%')

than mean scores for Ve at V02 max. This large di ff erenee • probably reflects the nonporportional increase in Ve

associated with increases in exercise above AT; caused by

the need to eliminate excess COz produced by metabolic

acidosis and erratic breathing patterns customarily observed

at high exercise intensities.

HR {bts/min)

52

--- -~- ---------180

170 - - - - - - - - - - -

160

150

140 -

FIGURE 6. The Result of Asymptotic

Effects on the Relationship Between

Heart Rate and Oxygen Consumption.

• AT versus Aatrand•s prediction of vo2 max. The com-

parison of AT to .Astrand•s prediction ot vo2 max.is based

primarily on findings associated with the vo2 parameter.

A review of findings show that the comparison of trial

parameters produced results very similar to those found

for comparisons of Kr and vo2 max. A summary of the~ results

is shown in Table 5. There existed no significant coefficients

of correlation which could be used for identif;ring Jtr as a

valid indicator of functional capacity. Furthurmore, there • was a significant difference between means of V02 at, AT and . -Astrand 1 s V02 max; identifying a separation of measurement.

Figure 7 represents this relationship. From this figure it

might be noticed that a ranking order can be~ establ~shed for

the three trials_ based on paramete;r: means.

The examin~tion of _AT validity as a measure of endurance

performance is bas_ed on its comparison to the Pwc170 and the

1.5 m1 run trials. Sinning (1975) indicates that the Pwc 170 trial identifies the· work capacity of an individual associat-

ed with cardiac efficiency. Whereast the 1.5 mi run repre-

sents afield measure f'"rom which functional 1measurements are

ascribed. Therefore, any similarities between parameters

of Kl and enduranoe performance trials suggests that Kl

represents a val.id test for assessing function from perform-

ance measurements.

100

Percentage of V02 max 90

80

·,,

54

V02max

AS TR AND -PRED:-

I. 5mi - run -

.,._ A T-

.- PWC-

VO 2 (L/min)

V02max

- AT_ ,_ P WC -

ve (L/min)

1.5 mi - run (

I. 5mi ,_,,. run (2)

- AT-r- PWC -

.

HR (bts/min)

FIGURE 7. Mean Differences Between

Parameters for Trials of Function

Capacity and Endurance Performance.

( I ) Refers to 1.5 mi run using terminal

heart rate.

(2) Refers to 1.5 mi run using a me on

heart rote for the trial.

55

K£ versus Pwc170• The comparison of M and Pwc 170 parameters produced results supporting and opposing the

validity of 1'1X for measuring function from performance

measures. The comparison of vo 2 requirements between trials

suggests the possibility of Kr being similar to PWC 170•

The coefficient of correlation (r=.80) found for this

comparison was significant. In addition, it more closely

approximates a positive relationship than that found for

functional measures. Furthurmore, mean scores reveal that

the 6% difference between trials exercise requirements

represents no significant difference as described by tests

of means paired differences.

These findings imply that the metabolic demand for the

Kr and the PWC170 may be similar. This similarity may be

directly related to the submaximal level of performance

exhibited by both trials. The PWc170 is considered to be a

test eliciting a performance response of 70-80,% max, while

AT is purported to exist at a performance level of approxi-

mately 85% max. This suggests that the Pwc170 performance

range borders that of AT, thereby reducing variability and

increasing validity; which is supported by the significant

coefficient of correlation and the la.ck of mean differences.

The absence of a significant coefficient of correlation • for the Ve parameter may be attributed to the comparison of

nonlinear ventilatory responses at AT with linear responses

.56

at PWC 170• As there is no d1ff erence between mean.s, the low

coefficient of correlation may be related to subject

variability.

The examination of heart rate responses for trials • paralleled findings of the Ve comparison. The coefficient

of correlation (Table 5) showed no significant expression

of AT as a measure of perf orman.oe. This low corr el at ion

may be identified as being related to variability 1nter-

ject ed by comparisons of heart rate responses for steady-

state versus nonsteady-state exercise. In addition, previous

discussion of heart rate parameters for submaximal exercise

indicates that responses are variable. Therefore, it

appears that heart rate ~t K! is not a va~id measure of

heart rate associated with Pwc170 •

This lack of validity does not necessarily mean that

trials are not similar. Results indicate that there is no

significant difference between trials' mean heart rate

responses. A:3 previous discussion indicates that heart rate

response above AT reflects asymptotic characteristics, and

Ka.rpovi.ch and Sinning ( 1971) indicate that as work demand

increases cardiac efficiency becomes limited by the inability

of stroke volume to significantly increase with increases

in heart rate, and DeVries ( 1968) suggests that this limita-

tion corresponds to a work intensity associated with a heart

rate of 170 bts/min; then the close relation of mean heart

rates may be attributed to optimum cardiac utilization

associated with trial responses.

AT versus 1.5 mi run. Of all trials reviewed, .AT inter-' relations with 1.5 mi run were most closely associated.

Comparisons tor trials produced similarities tor both

functional capacity and endurance performance. It produced

a significant coefficient of correlation (r=.82) for V02

comparisons.

Although this finding expresses AT validity it may be

somewhat restricted by limitations inherent to the trial • • These limitations may be dependent on V02 values represent-

ing predicted instead of measured responses. However, • estimated VO 2 at 1. 5 mi run represents an average exercise.

intensity; thereby al.lowing .AT to be compared to the 1.5 mi

run as a total measure. Therefore, if it is assumed that to

sustain activity over an extended time interval. the performer

must regulate aerobic processes to avoid exhaustion; then it

may be hypothesized that a performer ca.n perceive a point

of optimum aerobic utilization and maintain activity at this

level through increases and decreases in work output. This

implies that the 1. 5 mi run represents a maximum performance

level at which aerobic mechanisms predominate. As· JI:r has

already been identified with optimum aerobic ut111.zation, • this explains the close relations hip found for V02 comparison

between Kr and the 1. 5 mi run trials.

58

• The lack of a significant difference between V02 mearJ.s

for trials support this close correlation; however, 1.5 mi

run scores are approximately 3-5% higher. This higher value

may be a function of the averaging effect produced by large

changes in output observed during the final minute of the

trial. Therefore, the relatively small difference in means

and the significant coeffi.cient of correlation suggest

that ~ is a valid measure of aerobic function estimated • from V02 values associated with 1.5 mi run performance

reponses.

In reviewing heart rate responses for the 1.5 mi run,

terminal rates were found to be approaching maximal levels

(approximately 95% max). This finding does J:?.Ot support

previous discussion for AT validity. However, this measure

may be subject to limitations in that it does not represent

the heart rate response throughout the exercise and that

it also represents an inflated work output that the subjects

perceive as necessary to maximize performance.

Therefore, heart rate responses were averaged for the

duration of the trial. This procedure produced a deviation

between mean heart rate responses which was not significant.

This suggests that any similarity between heart rate response

for trials may be attributed to optimum cardiac response.

In comparing Kr to performance trials, parameters

suggest a greater degree of relation than previous measures

of functional capacity. It appears that the performance

level of AT more closely approximates that of performance

trials. In addition, the AT appears to represent a measure

of optimum aerobic util.ization described by performance

measurements ;;

CONCLUSIONS

From the review of relations for an.aerobic threshold,

circulorespiratory endurance and performance capacity, it

can be concluded that for active adult men: (1) Kr can be • reliably determined by nonlinear changes in the Ve exercise

• • intensity curve,· ( 2) Ve and VC>i parameters at AT are reliable

measiu-es of c1.rcul.oresp1ratory function.- ( J) V02 at AT

represents a valid measure of optimum aerobic ut111zat-1on . . . . . associated with endurance performance measures and (4) V02

at AT does not represent a measure or functional capacity . . described by V02 max.

IMPLICATIONS

Several implications have been discovered via the

examination of results for AT reliability and validity.

From these implications there appear to be several advantages

of utilizing AT as an alternate or supplemental index of

o1rculoresp1ratory function.

The most significant implication is ascribed by the

60

relation of A:!· and metabolic acidosis. As the onset of

metabolic acidosis is used to identify the llr, this point

of exercise presumably renects anaerobic processes.

However, the reliability of ~ at Jtr implies that the Kr

also identifies a measure of aerobic function; and as the

onset of metabolic acidosis reflects limitations of aerobic • pathways, it may be surmised that VOz at Kr identifies

optimum aerobic utilization~

Support for this implication can be observed by the

lack of a significant coefficient of correlation for the • • comparison of VOz measures between K! and V02 max." This

absence of validity implies that to 2 at llr must represent

some measurement other than aerobic capacity.

Additional implications may be attributed to the

identification of the point or optimum aerobic utilization.'

First,' it suggests that aerobic function may be examined

with respect to measurements of capacity and optimum

utilization.' This represents a significant difference; as

an individual may not be able to change capacity measurements

due to physiological limitations; however, optimum utilization

may reflect a variable measure. This may be an important

factor for evaluating training/conditioning programs for

athletes and cardiac rehabilitation patients.

Secondly,· the ability to measure the point of optimum

aerobic utilization implies that a separation in aerobic

61

and anaerobic function can be described. This suggests that

exercise tasks may be examined with respect to specific

metabolic charact erist i es.

Results also imply that lf! represents a measure which

requires less strenuous exercise. This is an important

implication, especially when related to the reliability of • the functional measure at lf!. As the V02 at lf! (approximates

85% vo2 max) occurs a.t submartmaJ. exercise, it may reduce

risks and motivational limitations associated with obtain-

ing reliable measures of function. Although the exercise

demand is lower and it approaches the exercise range (70 ...

80% max) above which Detry (1973) suggests as an area of

increased risks, it does not necessarily identify lf! B:S a

safer test; it only implies that- energy requirements

reflect exercise which might entail fewer physical risks.

Similarily, reduced physical risks may influence subjects

to be less inhibitive during exercise; thereby, reducing

some motivational limitations. This also has implication

for its use in circulorespiratory rehabilitation programs.

The relation between PI! and the 1.5 mi run involving

aerobic function implies that individuals may be capable

of adjusting exercise to control conditions of optimum

aerobic utilization during the performance of an exercise

task.

RECOMMENDA!L'IONS

As the results of this study appear to be promising

for the use of Al' as an alternate and/or supplement index

of functional measurement, fUrthur examination is in order.

This examination should be concerned with increasing the

population for which the .AT can be extrapolated. A larger

population might include areas of sex, age and training/

condit 1on1.ng level. • Procedurely, the det erm.1nat ion of nonlinear Ve

responses may be effectively improved through the use of

electronic ventilatory measuring instrumentation. This • would provide more accurate assessments of Ve responses.

It might also assist in establishing an on-line record • of Ve responses through which a procedure could be developed

for predicting AT during testing conditions. This would

provide a means for terminating testing with the onset • of nonlinear Ve responses; considered to be .K!.

LITER.A!I'URE CITED

Astrand, P.-o. 1952. Experimental Studies of Physical Working Capacity in Relation to Sex and Age Munksgaard, Copenhagen, Denmark

.Astrand, P. -o. and K. Rodahl 1970. Textbook of Work Physiology New York, McGraw-Hill Book Company pp. 9-20, 115-250, 277-315, 341-369

Astrand, P.-o. and s. Rhyming 1954. 11 A Nomogram for CaJ.culat1on of Aerobic Capacity (Ph;rsical Fitness} from Pul.se Rate during Submaximal Work." Journal of Applied Physiology 7:218

Balke, B. 1969. A simple field test for the assessment of physical. fitness. CARI report 63-18, Oklahoma City: Civil AeromedicaJ. Research Institute, Federal Aviation Agency, September, 1963 from Cooper, K. H. "Quantifying Physical Aotiv1ty--How and Why?" Journal of the South Carolina Medical Association Vol. 65 Supplement 1-12: 37-40

Beaver, W. L. 1973. 11 Water vapor corrections in oxygen consumption calculations" Journal of At>plied Ph:tsiology 35:928-931 .

Comroe, J. H. 1967. Phzsiology of Respiration Chicago: Year Book, 1965 p.192-198 from Wasserman, K., A. L. Van Kessel and G. c. Burton "Interactions of Physiological Mechanisms during Exercise" Journal of Applied Ph:rsiology 22:71-85

Cooper, K. H. 1969. "QUantifying Physical Activity--How and Why?" Journag of the.South Caro11na Med1ca1 .Association Vol. 5 Supplement 1-12:37-40

Davis, c. T. M. 1968. "Limitations to the Prediction of Maximum Oxygen Intake from Cardiac Frequency Measure-ments11 Journal of Applied Ph:vsiology 24:700

Detry, J. M. R. 1973. Exercise Testing and Training in Coronary Heart Disease Baltimore: The Williams and Wilkins Company

DeVries, H. A. 1968. Physiology of Exercise for Physical Education and Athletics New York: Wm. c. Brown Company Publishers

63

64

DeVries, H. A. and C. E. Kl.afo 1965. "Prediction of Maximal o2 Intake from Submaximal Tests" Journal of Sports Medicine &.Physical Fitness 5:207-214

Hill, A.·v., c. N. H. Long Exercise, Lactic Acid O:eygen--Parts I-III 11

Britain xcvii, 84

and H. Lupton 1924. "Muscular and the Supply and Utilization of Procedings of the Royal Societ:r,

Issekutz, B., Jr. and K. Rodahl quotient during exercise" Ph.ysiolosy 16:606-610

1961. 11 Respirator;y Journal of Applied

Karpovich, P. v. and w. E. Sinning 1971. Physiology of Muscular Activity Philadelphia: w. B. Saunders Company

Margaria, R. H. T. Edwards and D. B. Dill 1933. 11The Possible Mechanisms of Contracting and Paying the Oxygen Debt and the Role of Lactic Acid in Muscular Contraction" The .American Journal of Physiology 106: 689-71.5

Miller, A. T., Jr. 1968. Energy Metabolism Philadelphia: F. A. Davis Company

-Naimark, A., K. Wasserman and M. B. Mcilroy 1964. 11 Continuous measurements of ventilatory exchange ratio during exercise" Journal of Applied.Physiology 19: 644-652

Rochmis, P. and H. Blackburn 1971. "Exercise Tests: A Survey of Procedures, Safety, and Litigation Experience in Approximately 170, 000 Teststt Journal of the .America."! Medical Association 217:1

Shepard, R. J. 1969. Endurance Fitness Canada: University of Toronto Press

Sinning, W. E. 1975. E:;periments and Demonstrations in Exercise Physiology Philadelphia: w. B. Saunders Company PP• 27-33, 55-70

Sjostrand, T. 1947. "Changes in the Respiratory Organs of Workman at an Ore Smelting Works" Acta Medica Scandinavia Supplement 196:687-699

Taylor, H. L., E. Buskirk and A. Henschel 1955. "Maximal Oxygen Intake as an Objective Measure of Cardio-Respiratory l?erformance11 Journal of Apulied Physiology 8:73

65

Teraslinna, P~, A. H. Isma.11 and D. F. MacLeod 1966. 11Nomogram by Astrand and Rhyming as a Predictor of Maximum Oxygen Intake" Journal of App11ed.Ph:ysiologz 21 :513

Wahlund, H. 1948. 11 Dete:rm1nation of the Physical Working Capacity" Acta Medica Scandinavia Supplement 215

Wasserman, K. and M. :s. Mcilroy 1964. "Detecting the Threshold of Anaerobic Metabolism in Cardiac Patients

. During Exercise" The American Journal. of Cardiology 14: 844-852 . . . .

Wasserman, K., A. L. Va.n Kessel and G. C. Burton 1967. "Interaction of physiological mechanisms during exerciseu JC>umal of Applied Physiologx 22:71-85

Wasserman, K., B. J. Whipp, s. N. Koyal. and w. L. Beaver 1973• ".Anaerobic threshold and respiratory gas exchange during exercise" Journa], of Applied Ph:Ysiolog:r 35:236-243

Whipp, B. J., c. Seard and K. 'Wasserman 1970. "Oxygen defio1t-oJCYgen debt relationlllhips and efficieny of anaerobic work" Journal ot &rn1i,ed Ph:rs1olos:r 28: 452-456 . . .

Whipp, B. J. and K. Wasserman. 1972• "Oxygen uptake kinetics for various intensities or constant-load work" Journ!J.. of Applied Physiology JJ:J51-J56

Appendix A

Summary of Individual Descriptive Measures

Measures Skin.folds (mm)

Age Hgt Wgt 1 2 3 4 Subjects (yrs) (cm) (Kg)

1 22 198 75.t 8.8 10.4 12.·o a.o 2 21. 184 81.1 17.5 10.8 11.5 18.3

J 22 174 64.5 a.o 9.0 6.5 6.'3

4 23 177 76•;4 69·3 a.o 5.0 5.5 5 \ 25 172 65.1 10.3 12.0 13.5 7.0

6 23 184 75.1 11.0 9.0 7.0 5.0 7 21 178 75;;9 19•8 11•'8 11.8 13.5

8 22 182 12~·a· 16.0 12.3 14~5 13.0

9 23 178 72.5 18.0 12.J 14.5 13.'0

10 22 169 67.5 26.0 14~5 18.5 21.'8

Sk1nfo1d notat1on: 1 = front thigh 2 = subscapular ~ = triceps = iliac crest

Appendix B

Experimental Testing Series

Tests

Subjects 1 2 3 4

1 A c D B

2 B c D A

3 B c A D

4 c B D A

5 B c A D

6 c D A B

7 A c D B

8 c A D B

9 A B c D

10 B A c D

Test notation: A = PWC17o

run/ V02 max B = 1.5 mi C = AT1 D = AT2

68

Appendix C • V02 max Prediction from the 1.5 mi run

• 1•5 mi run vol max Fitness (min) (L min) Hating

9:.59 51.6 + Excell ant

11:.59-10:00 42•6-51•5 Good

13:.59-12:00 33.8-42.5 Fair

15:59-14:00 25.0-33.7 Poor

16:00 2.5•'0 Very Poor

Individual assessments of Max oxygen consumption from

the 1.5 mi run were calculated by: .

( 1), Finding the correct time interval. (column 1)

needed to complete test•'

( 2) F1nd1_ng the Max 02 consumption range (column 2)

associated with the test time.

( 3) · Using interpolation (see example below), Max o2 consumption was assessed for each individual.

Example: Test time = 11: 33; therefore the Max o2 consumption range was 42.6-51•6•

interpolating: 11:59 - 11:33 11:.59 - 10:00

x ·------51.6 - 42.6

therefore, the assessed Max o2 consumption = 42.6 + 1.96 = 44.6

Appendix D

Breath-by-breath Techniques in Assessing vo2 @ AT

Step 1: Arrangement of Instrumentation

Breathing Apparatus

Level I

OM-11 LB-2

Level II

Level I - sampling breath-by-breath Level II - analysis breath-by-breath

Honeywell Osoillo-

graph

Level III

Level III - recording analog signal/breath

Step 2a Instrumentation Calibrated

Step J: Standard samples of o2 and co 2 were introduced at Level II to produce standard analog signals. at Level III, for experimental breath-by-breath comparisons.

X = analog deflection of Oz (mm) for stand-ard sample

Y = analog deflection of co2 (mm) for standard

Step 4: Testing followed procedures described for Kr 1n the methodology.

Step 5: Analog signals associated with AT were extracted and examined for x• and yr deflections. x• and yr reflected changes of experimental measures.

Therefore, X (mm) ---------------- =

x• (mm) p02 of standard

sample

and

70

Y (mm)

pco2 of standard sample

Yt (mm) =-------· unknown pco2

Step 6: o2 and co2 vaJ.ues .were corrected for water vapor concentra-eions found at the mouth using Beaver•s.(1973) nomogram tor computing true o2 differences.

Step ?: .corrected values were applied in oxygen uptake formula•·

Measures 1

1 45.8 2 40.J 3 46.;8

4 48.l

5 38.8 6 42.0

7 170 8 180

9 190 10 170 11 186 12 172 13 86.2 14 88.9

15 99 16 82.2 17 13.1 18 11.5

71

Appendix E

Individual Raw Data

Subjects

2 3 4 5 6

40.9 49.7 37.0 50.9 51.0

40.1 53.1 38.0 46.7 50.4 43.3 .59·9 54.2 52.7 58~'6

41.6 52.4 50.6 54.7 65.2

43.4 3a.5 40.6 45.9 47.9 42.0 51.5 43.8 43.8 59.5 172 176 180 170 178 176 176 180 170 170

174 200 196 190 188

170 170 170 170 170

192 182 186 180 194 192 181 174 160 163

84.o 7'.3-3 70.7 76.6 97.0 90.3 72.7 99.9 76.0 91.5

89 107 104 93 121

85.3 70.3 77.4 77.4 72.0 11.6 14."2 10.6 14.5 14.'6

11.'5 15.-2 10.9 13.3 14.4

7

35.7 35.9 37.2 41.3

37.0 34.0

170 170 188

170 196 183

57.6 57.8

73 76.6 10.1 10.·2

[email protected] 8=HR@AT2 9=HR@vo2 .max 10=HR@Pwc170 [email protected] mi :run (terminal) 12=HR®1.5 mi run (average)

8 . 9 10

51.5 40.9 25.5 49.7 40.·1 29;9 54.5 46.5 46.2

50.1 42.8 38.6 47.0 37.5 27.0 50.8 51•8 24.9 166 170 170

170 172 174 170 192 196

170 170 170 174 195 160

158 183 160

79.6 73.4 45.6 90.5 72.7 42.9

94 101 92 84.5 60.1 58.0

14.7 11.7 7.3 14.2 11.5 8.5

The vita has been removed from the scanned document

THE BEL.ATION OF AN.AEROBIC THRESHOLD,

CIRCULORESPIR.ATORY ENDURANCE .AND

PERFOBM.ANCE CAPACITY IN

A~IVE .ADULT MEN

by

John Edwin Harper

(ABSTRACT)

The reliability of anaerobic threshold and the validity

of its use as an index of circulorespiratory endurance and

performance capacity were investigated using coefficients of

correlation and mean scores. Reliability was determined for

anaerobic threshold prediction using nonlinear cha.ng~s in . • the Ve exercise intensity curv€ and for indices associated

with anaerobic threshold. The validity of anaerobic

threshold was established through comparison of indices

related to recognized trials of functional capacity and

endurance performance.

Significant coefficients of reliability were produced

for predicting AT from nonlinear Ve responses. I

In addition,

respiratory indices associated with anaerobic threshold were

also found to be reliable measures of function.

The validity of anaerobic threshold indices was

specifically related to functional measures described by

performance capacity measurements. There was no evidence

to suggest that anaerobic threshold represented measures of

:functional capacity.

It was concluded that an.aerobic threshold represented

a reliable measure of optimum aerobic utilization which

closely followed functional measures associated with

performance capacity.

From results, several implications were posed for

the use of anaerobic threshold. First, anaerobic threshold

appeared to identify the metabolic components of exercise.

Second, its use reflected a functional measure of optimum

aerobic utilization. Third, it reflected exercise demand

that was less strenuous resulting in fewer physiological

and psychological limitations. Fourth, it implied that

performance could be evaluated with respect to aerobic/

anaerobic functions.

A description of the investigation and the comparisons

used for the determination of anaerobic threshold reliability

and validity are included.

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