AACVPR 2002

A Comparison of Equations for the Prediction of VO2 max in Elderly

Cardiac Patients.

Robert C. Lowe, University of Central FloridaRonald M. Williams, Baptist Medical Center

James W. Bryan III, Arkansas Sports Medicine

AACVPR 2002

Introduction

: Klinger TA ; McConnell TR ; Gardner JK Affiliation: Geisinger Health System, Dept. of Cardiology 21-60, 100 N. Academy Ave., Danville, PA 17822 Title:

Prescribing target heart rates without the use of a graded exercise test Source: Clinical Exercise Physiology 2001 Nov; 3(4): 207-12, 232-3 (15 ref) Journal Code: CLIN EXERC PHYSIOL Standard No: ISSN: 1520-8702 NLM Unique Identifier: 100883505 Language: English Abstract: Purpose: This study was performed to evaluate whether safe and effective target heart rates for outpatient cardiac rehabilitation patients could be derived using signs, symptoms, and ratings of perceived exertion without an exercise test.

Methods: Twenty-seven patients (23 M, 4 F; mean age 57 +/- 13), without entry exercise tests, were assigned target heart rates based on signs, symptoms, and ratings of perceived exertion during their beginning classes of a 12-week cardiac rehabilitation program. All patients later underwent a graded exercise test at Week 7.0 +/- 2.8 of the program. Target heart rates were calculated from this test using methods of 60-90% of maximum heart rate and 50-85% of heart rate reserve and compared to those based on signs, symptoms, and ratings of perceived exertion in cardiac rehabilitation classes. Low and high range values of each calculation method were compared and correlated.

Results: Low and high range values of target heart were different (p < 0.05) for each respective method of calculation. Target values derived in cardiac rehabilitation classes (84102) were within the ranges calculated using 60-90% of heart rate maximum (80-120). The high value (102) was also within the upper limit value of 85% of heart rate reserve (122). Low and high target heart rate values derived from rehabilitation classes had positive correlations (r= 0.51; p <- 0.007) with both traditional methods of target heart rate calculation. Exercise capacity, body composition, and psychological well-being improved as a result of cardiac rehabilitation.

Conclusion: Safe and effective target heart rates can be assigned based on clinical signs, symptoms, and ratings of perceived exertion without the use of a graded exercise test.

AACVPR 2002

Introduction

A specific activity questionnaire to measure the functional capacity of cardiac patients. AU:AuthorRankin SL; Briffa TG; Morton AR; Hung J AF:Author AffiliationDepartment of Human Movement, The University of Western Australia, Australia. SO:SourceThe American journal of cardiology, 1996 Jun 1, 77(14):1220-3 IS:ISSN0002-9149 AB:AbstractExercise testing is often performed in persons with cardiac disease to measure their functional

capacity. Physical activity questionnaires assessing functional capacity have been used a low-cost and convenient alternative to exercise testing, but have not been well validated against measured oxygen consumption in a cardiac population. This study assesses the ability of a simple, 13-item activity questionnaire, known as the Specific Activity Questionnaire (SAQ), to measure functional capacity prospectively in a large sample of cardiac patients. Ninety-seven consecutive cardiac outpatients (85 men and 12 women aged 59 +/- 10 years [mean +/- SD]) completed the SAQ before an elective symptom-limited treadmill test. Subjects returned within 10 days to repeat the treadmill test, following the same protocol, with the additional measurement of peak oxygen consumption, VO2 (ml x kg(-1)min(-1)), using open circuit spirometry. The SAQ score was significantly related to measured peak VO2(r=0.57, p<0.001). Stepwise multiple linear regression analysis found that the addition of patient age, height, and body weight to SAQ score improved the measurement of peak VO2, accounting for 51% of the sample variance (R=0.71, p<0.001). Peak VO2 was obtained from the following regression formula: [formula: see text]. Thus SAQ, a simple 13-item self-administered activity questionnaire, is able to provide a moderately good measure of functional capacity in cardiac patients and may be useful tool in studies of the cardiac population when formal exercise testing is impractical or uneconomical.

AACVPR 2002

Introduction

McConnell TR ; Klinger TA ; Gardner JK ; Laubach CA Jr. ; Herman CE ; Hauck CA Affiliation: Geisinger Medical Center, Penn State Geisinger Health System, Danville, Pennsylvania

Title: Cardiac rehabilitation without exercise tests for post-myocardial infarction and post-bypass surgery patients Source: Journal of Cardiopulmonary Rehabilitation 1998 Nov-Dec; 18(6): 458-63 (19 ref) Journal Code: J CARDIOPULM REHABIL Medline No: 99074596 PMID: 9857279 Standard No: ISSN: 0883-9212 Serial Identifier: SR0054698 NLM Unique Identifier: 8511296 Language: English Abstract: PURPOSE: To compare the progress of patients who were exercise tested before or during cardiac rehabilitation versus those patients who were not tested. METHODS: Eighty-eight (88) post-myocardial infarction patients and 141 post-bypass surgery patients had a symptom-limited exercise test before or during 12 weeks of cardiac rehabilitation. Another 125 post-myocardial infarction and 146 post-surgery patients were not tested. RESULTS: Caloric expenditure during class increased for the entire group (P < 0.001) from week 1 to week 12. Body weight decreased for the entire group as a result of cardiac rehabilitation (P < 0.001). Tricep skinfolds decreased for the entire group (P < 0.001) while subscapular skinfolds did not change (P = 0.28). The percent change from week 1 to week 12 for both groups was similar for all variables. No problems occurred during cardiac rehabilitation that required emergency medical management. CONCLUSIONS: Patients completing a 12-week cardiac rehabilitation program can be safely progressed in terms of their exercise capacity without an entry exercise test. This is desirable in a managed-care setting for reducing costs while maintaining effective patient care. Such factors as staff training and experience, institutional philosophy, patient referral patterns, and facility location must be considered before adopting a no-test policy.

AACVPR 2002

Purpose

McConnell, et al. (JCR 1998; 18:458-463) recently have provided support for not requiring a graded exercise test (GXT) prior to beginning cardiac rehabilitation. Such measures could lead to considerable cost savings to our overburdened healthcare system. In addition, Ainsworth, et al. (MENH 1993; 75-82) recently developed a gender-specific regression equation to predict maximal oxygen uptake (VO2max) in apparently healthy adults. The purpose of this study was to examine the validity of this equation when applied to an elderly cardiac population. Prior to performing a GXT, 24 consecutive cardiac patients (19 male and 5 female; 59+/-8 yr.) were asked how many times in the past 7 days they had performed vigorous exercise. The predicted VO2max (PRED) was then compared to three VO2max prediction equations (Bruce cardiac, CARDIAC; Bruce active, ACTIVE; and Bruce inactive, INACTIVE) as described by Milani, et al. (JCR 1996; 16:394-401). Data was analyzed by two-way ANOVA with repeated measures across prediction equations (CARDIAC, ACTIVE, INACTIVE, and PRED). No significant differences between males and females were observed (p>0.05). The pooled results indicated that VO2max predicted by CARDIAC (32.2+/-3.9 ml/kg/min) was significantly less (p<0.05) than VO2max predicted by ACTIVE (36.2+/-5.6 ml/kg/min), INACTIVE (37.1+/-6.4 ml/kg/min), or PRED (36.7+/-6.1 ml/kg/min). These results suggested that PRED produced similar results to ACTIVE and INACTIVE. However, PRED significantly overestimated VO2max compared to CARDIAC. In light of Milani and colleagues' (1996) conclusion that only CARDIAC accurately predicts VO2max in cardiac patients, the validity of using PRED in an elderly cardiac population must be questioned and warrants further study.

AACVPR 2002

Introduction

: Milani J ; Fernhall B ; Manfredi T Affiliation: University of New Mexico, Employee Health Promotion Program, Johnson Center, Box 40, Albuquerque, NM

87131-1251 Title: Estimating oxygen consumption during treadmill and arm ergometry activity in males with coronary artery disease Source: Journal of Cardiopulmonary Rehabilitation 1996 Nov-Dec; 16(6): 394-401 (21 ref) Journal Code: J CARDIOPULM REHABIL Medline No: 97138814 PMID: 8985798 Standard No: ISSN: 0883-9212 Serial Identifier: SR0054698 NLM Unique Identifier: 8511296 Language: English Abstract: Purpose. This study compared the accuracy of common clinical treadmill and arm ergometry equations in estimating the rate of oxygen consumption for males with coronary artery disease. Methods. Measured and estimated submaximal and maximal oxygen consumption (VO2sub and VO2max) were compared during clinical treadmill (TM) and arm ergometry (AE) graded exercise tests in 15 males with established coronary artery disease (CAD). Estimated VO2sub and VO2max were derived from popular modality specific estimation equations, including those of the American College of Sports Medicine, Bruce and colleagues, Balady and colleagues, and Manfre and colleagues. Results. The American College of Sports Medicine (ACSM) 1991 TM equation overestimated VO2sub from 0.3 +/- 0.6 to 1 +/- 0.7 metabolic equivalents (METS) and VO2max by 3 +/- 3 METS, whereas the Bruce Normal Submax and Bruce Cardiac Submax equations inaccurately estimated VO2sub from -1 +/- 0.6 to 0.9 +/- 0.7 METS. The Bruce Active Max and Bruce Sedentary Max equations overestimated VO2max from 1 +/- 2 to 2 +/- 2 METS, whereas the Bruce Cardiac Max equation accurately estimated oxygen consumption at maximal exercise. The ACSM and Manfre Healthy AE equations underestimated VO2sub at low and intermediate workloads from 0.4 +/- 0.4 to 0.8 +/- 0.4 METS. However, the Balady Male and Manfre Cardiac AE equations underestimated VO2 at each submaximal work load from 0.6 +/- 0.3 to 1 +/- 0.6 METS and at maximal work loads from 0.8 +/- 0.9 to 2 +/- 0.8 METS. The ACSM and Manfre Healthy AE equations accurately estimated VO2 at greater submaximal work loads and at maximal exercise. Conclusions. These data suggest that the ability to estimate VO2 in males with CAD is more accurately performed during nonweight-bearing arm activity, although the reason is not entirely understood, and significant inconsistencies exist in the ability to accurately estimate VO2 during treadmill exercise. These data further suggest concern regarding exercise prescription from estimated values derived from both treadmill and arm ergometry tests, because submaximal, and in some instances maximal, estimations were inaccurate. Future research should focus on the development of accurate estimations for those with CAD, primarily during submaximal work.

AACVPR 2002

Methods

Prior to performing a GXT, 24 consecutive cardiac patients (19 male and 5 female; 59(±8 yr.) were asked how many times in the past 7 days they had performed vigorous exercise.

AACVPR 2002

Equation

PRED = AGE + GENDER + DAYS OF EXERCISE* *Exercise must have been of a sufficient

intensity to cause ______ and lasted at least _______ minutes.

AACVPR 2002

Methods

The predicted VO2max (PRED) was then compared to three VO2max prediction equations (Bruce cardiac, CARDIAC; Bruce active, ACTIVE; and Bruce inactive, INACTIVE) as described by Milani, et al. (JCR 1996; 16:394-401).

Data was analyzed by two-way ANOVA with repeated measures across prediction equations (CARDIAC, ACTIVE, INACTIVE, and PRED).

AACVPR 2002

Results

No significant differences between males and females were observed (p>0.05).

The pooled results indicated that VO2max predicted by CARDIAC (32.2(3.9 ml/kg/min) was significantly less (p<0.05) than VO2max predicted by ACTIVE (36.2(5.6 ml/kg/min), INACTIVE (37.1(6.4 ml/kg/min), or PRED (36.7(6.1 ml/kg/min).

AACVPR 2002

Conclusion

These results suggested that PRED produced similar results to ACTIVE and INACTIVE. However, PRED significantly overestimated VO2max compared to CARDIAC.

In light of Milani and colleagues' (1996) conclusion that only CARDIAC accurately predicts VO2max in cardiac patients, the validity of using PRED in an elderly cardiac population must be questioned and warrants further study.

AACVPR 2002

Caveats

VO2 was not measured.Accuracy of self-report

AACVPR 2002

The End