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TRANSCRIPT
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.