Noninvasive Determinations of the Anaerobic Threshold* Reliability and Validity in Patients with COPO Michael] Belman, M.D., FC.C.R; Lawrence] Epstein, M.D.; Daniel Doornbos, M.D., FC.C.R; Janet D. Elashof.t Ph.D.; Spencer K. Koerner; M.D., FC.C.R; and Zab Mohsenifar; M.D., FC.C.R We compared the intraobserver and interobserver agreement of blood (BGT) and gas exchange (GET) methods for determination of the anaerobic threshold (AT) in patients with COPD. In addition, we determined the sensitivity and speciflcity of the gas exchange methods for determination of the AT. Two noninvasive methods, the V-slope (VS) and the ventilatory equivalents method (VEM) were compared with two blood sampling methods, the log standard HC03 (SB) vs log VOl (SBT) and base excess (BE) vs VOl (BET). Twenty-nine patients with COPD (FEV.
10 0
,-.....
0
30
60
0.250 0.000 0.000
90
••
.. 0.250
LOG STANDARD BICARBONATE METHOD
1.450
CD
1.400
••
•
•
W U
•
~
-0.100
0.000
LOG V02
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••
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0
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BASE EXCESS METHOD
"E
«
a:::
0.500
V02 (I/min)
WORK RATE (watts)
CD Ck:
""
, •
I
0.100
0.250
0.500
0.750
• •
1.000
1.250
V02 (I/min)
FIGURE 1. Graphs of the four methods used to determine the AT. The specific method for detecting an AT from the ~raphic deflelic acidosis was defined as a decrease of SB of 2.5 mEq/L. All 11 patients who did not develop a metabolic acidosis in that study had a chan~e in SB 0:::
1000
(/)
m
750
I
500
a
500
0
r(s)
W
N
0
Method
W
1000
Observer 2
Observer 1
Change in SB, mEqIL
""' E
"-'" N
a
>
•
250
0
0
250
500
•
• • r(s) r(p)
750
=.57 =.94
1000
1250
V02 (ml) - OBSERVER 1 FIGURE 3. Interobserver reliability determination for trial 1 using the standard bicarbonate method (SBT). The N =8 triangle represents those patients who did not have an AT detected by either observer, and the diamonds along the top and right borders represent patients who had an AT detected by only one observer. The r(p) value represents the correlation of those patients in whom an AT was detected on both occasions, whereas the r(s) includes all patients, whether or not the AT was detected by either observer. CHEST I 102 I 4 I OCTOBER. 1992
1031
Table 4-1nterobserver Reliability· Trial I
Trial 2
Method
r(s)
r(p) {n}
r(s)
r(p) {n}
Ventilatory equivalents V-Slope Standard bicarbonate Base-excess
.80 .86 .65 .70
.79 .97 .94 .96
.74 .77 .57 .48
.77 {II} .98 {7} .84 {I7} .96 {I8}
{II} {9} {I4} {I6}
*r(s) = Spearman's rank correlation coefficient; r(p) = Pearson's correlation coefficient; {n} = number ofpatients included in calculation ofr(p).
having an AT detected if an AT was seen on at least three of the four readings. Of the patients who developed a metabolic acidosis, the blood gas methods were more sensitive for determining an AT, detecting six of seven by BET and five of seven by SBT. The two GET methods each detected only four of seven. The specificity of the GET methods was poor, with a high number of false-positives. The sensitivity, specificity, and positive and negative predictive values ofthe GET methods are given in Table 5. We did not calculate specificity for the BGT methods since no attempt would be made to detect an AT in the absence of a metabolic acidosis. Knowledge of the development or absence of a metabolic acidosis would eliminate the possibility of false-positive AT determinations. DISCUSSION
We found a large degree of variability within and between trained observers in determining an AT by various arterial blood and gas exchange methods in patients with COPD. In addition, the GET methods frequently misclassified patients with respect to the N=29
~
HC03 ~ 2 meq/I
~HC03
22/29
7/29
~ VS SB BE
VEM 4/7
4/7
< 2 meq/I
5/7
6/7
~VS
VEM 7/22
5/22
FIGURE 4. Comparison of the ability of four methods to detect an AT in the presence of metabolic acidosis. A change in the standard bicarbonate (HC03 )2:2 mEq/L indicates the occurrence of a metabolic acidosis with exercise. Seven of the 29 patients developed a metabolic acidosis (left branch). The fractions along the bottom line of the left branch represent the number of patients detected correctly by each of the four AT methods (true-positives). Twenty two patients failed to develop a metabolic acidosis (right branch). The fractions on the bottom line of the right branch represent the number of patients in whom an AT was identi6ed by the VEM and V5 methods (false-positives). VEM is ventilatory equivalents method; VS, V-slope method; 5B, standard bicarbonate method; and BE, base-excess method.
1032
Table 5-Sensitivity, Specificity, and Predictive Values of the Gas Exchange Method Predictive Values Method
Sensitivity
Specificity
Positive
Ne~ative
Ventilatory equivalents, % V-Slope, %
57
68
36
83
57
77
44
85
presence of metabolic acidosis. Most of the previous studies which have reported high correlations between GET methods and LAT methods used either single observer determinations of an AT, or did not report reliability data when multiple observers were used. 10.12-15 Matsumura et aI, 11 in 1983, used multiple observers and found a high correlation between VEM and LAT (r= .962). However, they excluded two often patients from evaluation because an AT could not be detected by one or the other observer for both methods. Several studies which looked at reliability data did not find a high correlation between GET and LAT. Yeh et al,IH in 1983, found differences averaging 16 percent between the values of the \'02 at the AT determined by four independent exercise physiologists using GET methods. Using a similar protocol, Shimuizu et al l9 found a smaller variance among three readers (164 ml O/min), although like Matsumura et aI, II they excluded data that were considered uninterpretable by one or more readers. As shown in our results, exclusion of discordant data improves the intraobserver and interobserver agreement considerably. Green et aJ16 attempted to decrease the subjectivity and variability by using computer determinations of the AT by multiple regression analysis. They found a difference between the power output at the AT determined by LAT and GET of 48 percent. Gladden et aJ17 evaluated the correlation between GET and LAT determined by independent evaluators in nine different laboratories. In addition, they examined the agreement between GET and LAT determined by computer analysis. They found good intraobserver reliability (r>.97) but poor interobserver reliability (r = .81 for LAT and r = .70 for GET). In addition, there was poor correlation between LAT and GET (r= .53). The results were not improved by using computer analysis. In general, our results are in agreement with several of these previous studies. 16-18 In our study, we found a lower rate of development of metabolic acidosis (7 of 29) as compared to Sue et al. 6They found a metabolic acidosis in 11 of22 patients. This is most likely due to differences in our study populations. Their patients who developed metabolic acidosis had milder obstructive disease than those who did not develop acidosis. Group 1, in whom no acidosis was found, had an average FEV. and FVC of Noninvasive Determinations of Anaerobic Threshold (Belman et al)
1.16 and 2.29 L, compared to 1.23 and 3.12 L for group 2 with metabolic acidosis. The severity ofairway obstruction in our patients was similar to their group 1 patients with an average FEV 1 and FVC of 0.94 and 2.26 L, respectively. In a recent study by Punzel and co-workers,27 the patients who failed to develop an AT had significantly more obstnlction than those who did (FEV 1 1.96 vs 1.07). Of 24 patients with mild airway obstruction (FEV 1 mean = 1.80 Land FVC=3.10 L, approximately), Casaburi and co-workers5 found 19 of 24 patients in whom an AT was detected. In patients with COPD, impaired ventilatory mechanics may limit the rise in ventilation which occurs at the AT, and thus, limit the utility of the VEM. In a study by Elliot and colleagues28 of six patients with COPO, they found that detection of an AT from analysis of the respiratory exchange ratio (R) was better than the VEM. Subsequently, the V-slope method was proposed as superior in COPO patients, allowing identification of an inflection point which is independent of a blunted VEe Even though the V-slope was designed to improve detection in COPO patients, this new method has not previously been compared directly with other GET methods in these patients. We found that despite the severity of lung disease and limitation to VE, the VEM was as successful as the V-slope method in detecting an AT. Moreover, in the original study of the V-slope,20 visual detection of the inflection point was frequently unsuccessful even in normal subjects. The V-slope was detected by all observers in only five of their ten subjects. The discrepancy between the r(p) and r(s) values is due to the exclusion of patients from the calculation of r(p) when a threshold was not detected on both of the determinations. Inclusion of all trials in the calculation of r(s) resulted in a poorer correlation. The r(p) values were considerably better for all comparisons apart from the VEM for observer 1. One explanation for the failure of both observers to always find an AT may be a result of the reduced V02max in these patients. Even if an AT occurred, it would of necessity be close to the measured maximum V02. Thus, there is a limit to the number of measurement points that occur after the AT, making detection of the inflection point in all methods more difficult. It is possible that better agreement could be reached in studies ofnormal individuals in whom the AT inflection point is more clearly defined. However, as noted above, even in studies of normal subjects with high levels ofV02max, there has not always been good interobserver correlations. 17 .1R
Although blood levels of SB and BE are helpful in detecting the presence of acidemia, there was still disagreement with respect to the determination of the actual threshold point in patients with moderate to
severe COPO. The dual problems of low sensitivity and specificity of the GET methods and the relatively poor interobserver and intraobserver reliability of all the methods, suggests that the potential is great for disagreement not only in determining the presence or absence of an AT, but also in fixing the level of V02 at which it occurs. Because of these difficulties, the utility of the AT in patients with COPO as a marker of circulatory dysfunction or as a guide to exercise training intensity is questionable. 5 Moreover, even though both observers were experienced in the interpretation of exercise studies and had reviewed the methods of analysis prior to the actual readings, there was a difference in the reliability of their measurements. We would expect to find a similar problem with the reliability of measurements made by other trained and experienced observers. Further training and auditing of personnel in one laboratory to correct discrepant results could conceivably reduce the interobserver disagreement. This will be evaluated in a future stud}: In the interim, we believe our results show that considerable caution should be used in making clinical decisions on the basis of noninvasive AT determinations in COPO patients. REFERENCES 1 Hill AV, Long CNH, Lupton H. Muscular exercise, lactic acid, and the supply and utilization of oxygen, VI: the oxygen debt at the end of exercise. Proc R Soc Lond 1924; 97: 127-37 2 Owles WH. Alterations in the lactic acid content of the blood as a result of light exercise, and associated changes in the CO 2 combining power of the blood and in the alveolar CO2 pressure. J Physiol 69:214-37 3 Wasserman K, McIlroy MB. Detecting the threshold of anaerobic metabolism. Am J Cardioll964; 14:844-52 4 Davis JA, Frank MH, Whipp BJ, Wasserman K. Anaerobic threshold alterations caused by endurance training in middleaged men. J Appl Physiol1976; 46:1039-46 5 Casaburi R, Patessio A, Ioli F, Zanaboni S, Donner CF, Wasserman F. Reductions in exercise lactic acidosis and ventilation as a result of exercise training in patients with obstnlctive lung disease. Am Rev Respir Dis 1991; 143:9-18 6 Sue DY, Wasserman K, Moricca RB, Casaburi R. Metabolic acidosis during exercise in patients with chronic obstructive pulmonary disease. Chest 1988; 94:931-38 7 Casaburi R, Wasserman K. Exercise rehabilitation in patients with COPD. N Engl J Med 1986; 314:1509-11 8 Brooks GA. Anaerobic threshold: review of the concept and directions for future research. Med Sci Sports Exerc 1985; 17:22-31 9 Beaver WL, Wasserman K, Whipp BJ. Improved detection of lactate threshold during exercise using a log-log transformation. J Appl Physioll985; 59:1936-40 10 Caiozzo VJ, Davis JA, Ellis JF, Azus JL, Vandagriff R, Prietto CA, et ale A comparison of gas exchange indices used to detect the anaerobic threshold. J Appl Physiol 1982; 53: 1184-89 11 Matsumura N, Nishijima H, Kojima S, Hashimoto F, Minami M, Yasuda H. Determination of anaerobic threshold for assessment of functional state in patients with chronic heart failure. Circulation 1983; 68:360-67 12 Dickstein K, Barvik S, Aarsland T, Snapinn S, Karlsson J. A CHEST I 102 I 4 / OCTOBER, 1992
1033
13
14
15
16 17 18
19
comparison of methodologies in detection of the anaerobic threshold. Circulation 1990; 81 (suppl 2):38-46 Davis JA, Vodak ~ Wilmore JH, Vokad J, Kurtz E Anaerobic threshold and maximal aerobic power for three modes of exercise. J Appl Physiol1976; 41:544-50 Ivy JL, Withers RT, Van Handel PJ, Elger DH, Costill DL. Muscle respiratory capacity and fiber type as determinants of the lactate threshold. J Appl Physioll980; 48:523-27 Simon J, Young JL, Gutin B, Blood DK, Case R. Lactate accumulation relative to the anaerobic and respiratory compensation thresholds. J Appl Physiol 1983; 54: 13-17 Green HJ, Hughson RL, Orr G~ Ranney DA. Anaerobic threshold, blood lactate, and muscle metabolites in progressive exercise. J Appl Physioll983; 54:1032-38 Gladden BL, Yates J~ Stremel R~ Stamford BA. Gas exchange and lactate anaerobic thresholds: inter- and intraevaluator agreement. J Appl Physiol 1985; 58:2082-89 Yeh M~ Gardner RM, Adams TD, Yanowitz FG, Crapo RO. Anaerobic threshold: problems of determination and validation. J Appl Physioll983; 55:1178-86 Shimuizu M, Myers J, Buchanan N, Walsh D, Kraemer M, McAuley ~ et al. The ventilatory threshold: method, protocol, and evaluator agreement. Am Heart J 1991; 122:509-15
1034
20 Beaver WL, Wasserman K, Whipp BJ. A new method for detecting anaerobic threshold by gas exchange. J Appl Physiol 1986; 60:2020-27 21 American Thoracic Society. Standardization of spirometry1987 update. Am Rev Respir Dis 1987; 136:1285-98 22 Boren HG, Cory RC, Syner JC. Veterans administration army cooperative study of pulmonary function, II: the lung volume and its subdivisions in normal men. Am J Med 1966; 41:96-114 23 Murray JF. The normal lung. Philadelphia: WB Saunders, 1976 24 Siggaard-Anderson 0, Engel K. A new acid-base nomogram: an improved method for the calculation of the relevant blood acidbase data. Scand J Clin Lab Invest 1960; 12: 177 25 Davis JA, Frank MH, Whipp BJ, Wasserman K. Anaerobic threshold alterations caused by endurance training in middleaged men. J Appl Physiol 1976; 41:544-50 26 Colton T. Statistics in medicine. Boston: Little, Brown & Co, 1974 27 Punzel PA, Hies AL, Kaplan RM, Prewitt LM. Maximum intensity exercise training in patients with chronic obstructive pulmonary disease. Chest 1991; 100:618-23 28 Elliot CG, Cromar B, Adams TD, Crapo RO, Yeh M~ Gardner RM. Measurement of anaerobic threshold in chronic airflow obstruction. Respiration 1987; 52:7-15
Noninvasive Determinations of Anaerobic Threshold (Be/man at all
10 0
,-.....
0
30
60
0.250 0.000 0.000
90
••
.. 0.250
LOG STANDARD BICARBONATE METHOD
1.450
CD
1.400
••
•
•
W U
•
~
-0.100
0.000
LOG V02
W
-1
CD
-2 0.000
••
(/)
«
0
-0.200
x
0
•• •
w
•
(/)
1.350 -0.300
•
(/) (/)
.-« -.J
1.250
Q)
0
«
1.000
CT
u
0 Z
0.750
BASE EXCESS METHOD
"E
«
a:::
0.500
V02 (I/min)
WORK RATE (watts)
CD Ck:
""
, •
I
0.100
0.250
0.500
0.750
• •
1.000
1.250
V02 (I/min)
FIGURE 1. Graphs of the four methods used to determine the AT. The specific method for detecting an AT from the ~raphic deflelic acidosis was defined as a decrease of SB of 2.5 mEq/L. All 11 patients who did not develop a metabolic acidosis in that study had a chan~e in SB 0:::
1000
(/)
m
750
I
500
a
500
0
r(s)
W
N
0
Method
W
1000
Observer 2
Observer 1
Change in SB, mEqIL
""' E
"-'" N
a
>
•
250
0
0
250
500
•
• • r(s) r(p)
750
=.57 =.94
1000
1250
V02 (ml) - OBSERVER 1 FIGURE 3. Interobserver reliability determination for trial 1 using the standard bicarbonate method (SBT). The N =8 triangle represents those patients who did not have an AT detected by either observer, and the diamonds along the top and right borders represent patients who had an AT detected by only one observer. The r(p) value represents the correlation of those patients in whom an AT was detected on both occasions, whereas the r(s) includes all patients, whether or not the AT was detected by either observer. CHEST I 102 I 4 I OCTOBER. 1992
1031
Table 4-1nterobserver Reliability· Trial I
Trial 2
Method
r(s)
r(p) {n}
r(s)
r(p) {n}
Ventilatory equivalents V-Slope Standard bicarbonate Base-excess
.80 .86 .65 .70
.79 .97 .94 .96
.74 .77 .57 .48
.77 {II} .98 {7} .84 {I7} .96 {I8}
{II} {9} {I4} {I6}
*r(s) = Spearman's rank correlation coefficient; r(p) = Pearson's correlation coefficient; {n} = number ofpatients included in calculation ofr(p).
having an AT detected if an AT was seen on at least three of the four readings. Of the patients who developed a metabolic acidosis, the blood gas methods were more sensitive for determining an AT, detecting six of seven by BET and five of seven by SBT. The two GET methods each detected only four of seven. The specificity of the GET methods was poor, with a high number of false-positives. The sensitivity, specificity, and positive and negative predictive values ofthe GET methods are given in Table 5. We did not calculate specificity for the BGT methods since no attempt would be made to detect an AT in the absence of a metabolic acidosis. Knowledge of the development or absence of a metabolic acidosis would eliminate the possibility of false-positive AT determinations. DISCUSSION
We found a large degree of variability within and between trained observers in determining an AT by various arterial blood and gas exchange methods in patients with COPD. In addition, the GET methods frequently misclassified patients with respect to the N=29
~
HC03 ~ 2 meq/I
~HC03
22/29
7/29
~ VS SB BE
VEM 4/7
4/7
< 2 meq/I
5/7
6/7
~VS
VEM 7/22
5/22
FIGURE 4. Comparison of the ability of four methods to detect an AT in the presence of metabolic acidosis. A change in the standard bicarbonate (HC03 )2:2 mEq/L indicates the occurrence of a metabolic acidosis with exercise. Seven of the 29 patients developed a metabolic acidosis (left branch). The fractions along the bottom line of the left branch represent the number of patients detected correctly by each of the four AT methods (true-positives). Twenty two patients failed to develop a metabolic acidosis (right branch). The fractions on the bottom line of the right branch represent the number of patients in whom an AT was identi6ed by the VEM and V5 methods (false-positives). VEM is ventilatory equivalents method; VS, V-slope method; 5B, standard bicarbonate method; and BE, base-excess method.
1032
Table 5-Sensitivity, Specificity, and Predictive Values of the Gas Exchange Method Predictive Values Method
Sensitivity
Specificity
Positive
Ne~ative
Ventilatory equivalents, % V-Slope, %
57
68
36
83
57
77
44
85
presence of metabolic acidosis. Most of the previous studies which have reported high correlations between GET methods and LAT methods used either single observer determinations of an AT, or did not report reliability data when multiple observers were used. 10.12-15 Matsumura et aI, 11 in 1983, used multiple observers and found a high correlation between VEM and LAT (r= .962). However, they excluded two often patients from evaluation because an AT could not be detected by one or the other observer for both methods. Several studies which looked at reliability data did not find a high correlation between GET and LAT. Yeh et al,IH in 1983, found differences averaging 16 percent between the values of the \'02 at the AT determined by four independent exercise physiologists using GET methods. Using a similar protocol, Shimuizu et al l9 found a smaller variance among three readers (164 ml O/min), although like Matsumura et aI, II they excluded data that were considered uninterpretable by one or more readers. As shown in our results, exclusion of discordant data improves the intraobserver and interobserver agreement considerably. Green et aJ16 attempted to decrease the subjectivity and variability by using computer determinations of the AT by multiple regression analysis. They found a difference between the power output at the AT determined by LAT and GET of 48 percent. Gladden et aJ17 evaluated the correlation between GET and LAT determined by independent evaluators in nine different laboratories. In addition, they examined the agreement between GET and LAT determined by computer analysis. They found good intraobserver reliability (r>.97) but poor interobserver reliability (r = .81 for LAT and r = .70 for GET). In addition, there was poor correlation between LAT and GET (r= .53). The results were not improved by using computer analysis. In general, our results are in agreement with several of these previous studies. 16-18 In our study, we found a lower rate of development of metabolic acidosis (7 of 29) as compared to Sue et al. 6They found a metabolic acidosis in 11 of22 patients. This is most likely due to differences in our study populations. Their patients who developed metabolic acidosis had milder obstructive disease than those who did not develop acidosis. Group 1, in whom no acidosis was found, had an average FEV. and FVC of Noninvasive Determinations of Anaerobic Threshold (Belman et al)
1.16 and 2.29 L, compared to 1.23 and 3.12 L for group 2 with metabolic acidosis. The severity ofairway obstruction in our patients was similar to their group 1 patients with an average FEV 1 and FVC of 0.94 and 2.26 L, respectively. In a recent study by Punzel and co-workers,27 the patients who failed to develop an AT had significantly more obstnlction than those who did (FEV 1 1.96 vs 1.07). Of 24 patients with mild airway obstruction (FEV 1 mean = 1.80 Land FVC=3.10 L, approximately), Casaburi and co-workers5 found 19 of 24 patients in whom an AT was detected. In patients with COPD, impaired ventilatory mechanics may limit the rise in ventilation which occurs at the AT, and thus, limit the utility of the VEM. In a study by Elliot and colleagues28 of six patients with COPO, they found that detection of an AT from analysis of the respiratory exchange ratio (R) was better than the VEM. Subsequently, the V-slope method was proposed as superior in COPO patients, allowing identification of an inflection point which is independent of a blunted VEe Even though the V-slope was designed to improve detection in COPO patients, this new method has not previously been compared directly with other GET methods in these patients. We found that despite the severity of lung disease and limitation to VE, the VEM was as successful as the V-slope method in detecting an AT. Moreover, in the original study of the V-slope,20 visual detection of the inflection point was frequently unsuccessful even in normal subjects. The V-slope was detected by all observers in only five of their ten subjects. The discrepancy between the r(p) and r(s) values is due to the exclusion of patients from the calculation of r(p) when a threshold was not detected on both of the determinations. Inclusion of all trials in the calculation of r(s) resulted in a poorer correlation. The r(p) values were considerably better for all comparisons apart from the VEM for observer 1. One explanation for the failure of both observers to always find an AT may be a result of the reduced V02max in these patients. Even if an AT occurred, it would of necessity be close to the measured maximum V02. Thus, there is a limit to the number of measurement points that occur after the AT, making detection of the inflection point in all methods more difficult. It is possible that better agreement could be reached in studies ofnormal individuals in whom the AT inflection point is more clearly defined. However, as noted above, even in studies of normal subjects with high levels ofV02max, there has not always been good interobserver correlations. 17 .1R
Although blood levels of SB and BE are helpful in detecting the presence of acidemia, there was still disagreement with respect to the determination of the actual threshold point in patients with moderate to
severe COPO. The dual problems of low sensitivity and specificity of the GET methods and the relatively poor interobserver and intraobserver reliability of all the methods, suggests that the potential is great for disagreement not only in determining the presence or absence of an AT, but also in fixing the level of V02 at which it occurs. Because of these difficulties, the utility of the AT in patients with COPO as a marker of circulatory dysfunction or as a guide to exercise training intensity is questionable. 5 Moreover, even though both observers were experienced in the interpretation of exercise studies and had reviewed the methods of analysis prior to the actual readings, there was a difference in the reliability of their measurements. We would expect to find a similar problem with the reliability of measurements made by other trained and experienced observers. Further training and auditing of personnel in one laboratory to correct discrepant results could conceivably reduce the interobserver disagreement. This will be evaluated in a future stud}: In the interim, we believe our results show that considerable caution should be used in making clinical decisions on the basis of noninvasive AT determinations in COPO patients. REFERENCES 1 Hill AV, Long CNH, Lupton H. Muscular exercise, lactic acid, and the supply and utilization of oxygen, VI: the oxygen debt at the end of exercise. Proc R Soc Lond 1924; 97: 127-37 2 Owles WH. Alterations in the lactic acid content of the blood as a result of light exercise, and associated changes in the CO 2 combining power of the blood and in the alveolar CO2 pressure. J Physiol 69:214-37 3 Wasserman K, McIlroy MB. Detecting the threshold of anaerobic metabolism. Am J Cardioll964; 14:844-52 4 Davis JA, Frank MH, Whipp BJ, Wasserman K. Anaerobic threshold alterations caused by endurance training in middleaged men. J Appl Physiol1976; 46:1039-46 5 Casaburi R, Patessio A, Ioli F, Zanaboni S, Donner CF, Wasserman F. Reductions in exercise lactic acidosis and ventilation as a result of exercise training in patients with obstnlctive lung disease. Am Rev Respir Dis 1991; 143:9-18 6 Sue DY, Wasserman K, Moricca RB, Casaburi R. Metabolic acidosis during exercise in patients with chronic obstructive pulmonary disease. Chest 1988; 94:931-38 7 Casaburi R, Wasserman K. Exercise rehabilitation in patients with COPD. N Engl J Med 1986; 314:1509-11 8 Brooks GA. Anaerobic threshold: review of the concept and directions for future research. Med Sci Sports Exerc 1985; 17:22-31 9 Beaver WL, Wasserman K, Whipp BJ. Improved detection of lactate threshold during exercise using a log-log transformation. J Appl Physioll985; 59:1936-40 10 Caiozzo VJ, Davis JA, Ellis JF, Azus JL, Vandagriff R, Prietto CA, et ale A comparison of gas exchange indices used to detect the anaerobic threshold. J Appl Physiol 1982; 53: 1184-89 11 Matsumura N, Nishijima H, Kojima S, Hashimoto F, Minami M, Yasuda H. Determination of anaerobic threshold for assessment of functional state in patients with chronic heart failure. Circulation 1983; 68:360-67 12 Dickstein K, Barvik S, Aarsland T, Snapinn S, Karlsson J. A CHEST I 102 I 4 / OCTOBER, 1992
1033
13
14
15
16 17 18
19
comparison of methodologies in detection of the anaerobic threshold. Circulation 1990; 81 (suppl 2):38-46 Davis JA, Vodak ~ Wilmore JH, Vokad J, Kurtz E Anaerobic threshold and maximal aerobic power for three modes of exercise. J Appl Physiol1976; 41:544-50 Ivy JL, Withers RT, Van Handel PJ, Elger DH, Costill DL. Muscle respiratory capacity and fiber type as determinants of the lactate threshold. J Appl Physioll980; 48:523-27 Simon J, Young JL, Gutin B, Blood DK, Case R. Lactate accumulation relative to the anaerobic and respiratory compensation thresholds. J Appl Physiol 1983; 54: 13-17 Green HJ, Hughson RL, Orr G~ Ranney DA. Anaerobic threshold, blood lactate, and muscle metabolites in progressive exercise. J Appl Physioll983; 54:1032-38 Gladden BL, Yates J~ Stremel R~ Stamford BA. Gas exchange and lactate anaerobic thresholds: inter- and intraevaluator agreement. J Appl Physiol 1985; 58:2082-89 Yeh M~ Gardner RM, Adams TD, Yanowitz FG, Crapo RO. Anaerobic threshold: problems of determination and validation. J Appl Physioll983; 55:1178-86 Shimuizu M, Myers J, Buchanan N, Walsh D, Kraemer M, McAuley ~ et al. The ventilatory threshold: method, protocol, and evaluator agreement. Am Heart J 1991; 122:509-15
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Noninvasive Determinations of Anaerobic Threshold (Be/man at all
