A Comparison of Equations for the Prediction of VO2

max in Elderly Cardiac Patients.

Robert C. Lowe, University of Central Florida

Ronald M. Williams, Baptist Medical Center

James W. Bryan III, Arkansas Sports Medicine

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Introduction

❚ Milani J ; Fernhall B ; Manfredi T ❙ Estimating oxygen consumption during treadmill and

arm ergometry activity in males with coronary artery disease.

❙ Journal of Cardiopulmonary Rehabilitation 1996 Nov-Dec; 16(6): 394-401.

❚ 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.

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Introduction

❚ McConnell TR ; Klinger TA ; Gardner JK ; Laubach CA Jr. ; Herman CE ; Hauck CA ❙ Cardiac rehabilitation without exercise tests for

post-myocardial infarction and post-bypass surgery patients.

❙ Journal of Cardiopulmonary Rehabilitation 1998 Nov-Dec; 18(6): 458-63.

❚ Patients completing a 12-week cardiac rehabilitation program can be safely progressed in terms of their exercise capacity without an entry exercise test.

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Introduction

❚ Klinger TA ; McConnell TR ; Gardner JK ❙ Prescribing target heart rates without the use of a

graded exercise test.❙ Clinical Exercise Physiology 2001 Nov; 3(4): 207-12,

232-3.

❚ 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.

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Introduction❚ Rankin SL; Briffa TG; Morton AR

❙ A specific activity questionnaire to measure the functional capacity of cardiac patients.

❙ The American Journal of Cardiology, 1996 Jun 1, 77(14):1220-3

❚ 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.

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Equation

❚ Ainsworth, et al. (MENH 1993; 75-82) ❚ VO2max = 65.0 + 1.8(Frequency) - 10.0

(Gender) - 0.3(Age) - 0.6(BMI)❙ Where:❙ Frequency = number of strenuous exercise

sessions (at least 15 minutes) in the past 7 days.❙ Gender = 0 (male) or 1 (female)❙ Age = years❙ BMI = weight(kg)/height(m)2

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Purpose

❚ The purpose of this study was to examine the validity of this equation when applied to an elderly cardiac population.

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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.

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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).

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Methods

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

Male

Cardiac

19

Active

19

Inactive

19

Predicted

19

Female 5 5 5 5

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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).

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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.

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Caveats

❚ VO2 was not measured.

❚ Accuracy of self-report❚ “Such factors as staff training and experience,

institutional philosophy, patient referral patterns, and facility location must be considered before adopting a no-test policy.” Milani, et al. 1998

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The End