The prediction of functional capacity in active coronary artery disease patients using a physical activity questionnaire

This investigation examined the ability of the Veterans Specific Activity Questionnaire (VSAQ) to predict the functional capacities (expressed in metabolic equivalents or METs) of twenty male participants previously diagnosed with CAD who were referred for exercise testing as part of their participation in a community based exercise program. On the morning of their normally scheduled GXT, each individual completed the VSAQ and was administered a maximal exercise test on a treadmill utilizing a ramp style protocol based on their self estimation of functional capacity. Respiratory gas exchange values were recorded throughout and analyzed via stepwise linear regression with respect to several experimental and demographic variables such as age, BMI, percent body fat and time since entering a cardiac maintenance exercise program. The only variable to contribute significantly to the prediction of FC with regard to exercise capacity as measured by respiratory gas analysis was the VSAQ. The VSAQ explained 22.% of the variance in actual performance and this variable only showed a modest association with the criterion measure (r = 0.47 SEE 2.25, p <0.05). A similar finding was noted when this criterion of exercise performance was estimated from treadmill speed and grade equations. In this case, the VSAQ accounted for 34% of the variance in exercise performance, i.e., r=0.58 (SEE 2.16, p <0.05). The final regression equation by which the VSAQ might be used to predict exercise capacity by the gas exchange criterion was: METs = 4.21 + 0.50(VSAQ). The final regression equation for prediction of MET exercise capacity by speed/grade at peak exercise was: METs = 4.60 + 0.65(VSAQ).