Bruce Treadmill Vo2peak Prediction Equations Are Inaccurate for Cancer Survivors

Abstract

Background Cardiorespiratory function measured as peak volume of oxygen consumption (Vo2peak) predicts all-cause mortality and dictates exercise prescription for cancer survivors (CS). It is imperative that Vo2peak values are reliable, as using inaccurate values may invalidate the exercise program and is unsafe. The Bruce treadmill protocol is commonly used for Vo2peak testing but may not be accurate for CS because of its higher intensity. A cancer-specific treadmill (CANCER) protocol and corresponding prediction equations has been validated, yet the Bruce protocol is most used, also using estimation equations. It is unknown if the Bruce protocol is appropriate for CS. The purpose of this study was to determine whether the Bruce protocol prediction equations provide accurate estimations of Vo2peak for CS by comparing it against Vo2peak values from the CANCER protocol using gas analysis (CANCERmet) and prediction equations (CANCERest). Methods Forty-seven subjects completed both CANCER and Bruce protocols 1 week apart in randomized order. Actual and predicted Vo2peak from CANCERmet and CANCERest, respectively, were compared to estimated Vo2peak from the Bruce. Results Vo2peak values were significantly lower in CANCERmet and CANCERest compared to the Bruce (P < 0.05); however, peak heart rate, systolic blood pressure, and rate pressure product were significantly higher using the CANCER protocol (P < 0.05). Conclusion The Bruce protocol and corresponding Vo2peak prediction equations do not appear accurate for CS, as Vo2peak is significantly overpredicted, despite yielding lower physiological values of maximal exertion. The CANCER treadmill protocol should remain the gold standard for assessing cardiorespiratory function in CS.