Exercise training intensity determination in cardiovascular rehabilitation: Should the guidelines be reconsidered?

Aims: In the rehabilitation of cardiovascular disease patients a correct determination of the endurance-type exercise intensity is important to generate health benefits and preserve medical safety. It remains to be assessed whether the guideline-based exercise intensity domains are internally consistent and agree with physiological responses to exercise in cardiovascular disease patients. Methods: A total of 272 cardiovascular disease patients without pacemaker executed a maximal cardiopulmonary exercise test on bike (peak respiratory gas exchange ratio > 1.09), to assess peak heart rate (HRpeak), oxygen uptake (VO2peak) and cycling power output (W-peak). The first and second ventilatory threshold (VT1 and VT2, respectively) was determined and extrapolated to %VO2peak, %HRpeak, %heart rate reserve (%HRR) and %W-peak for comparison with guideline-based exercise intensity domains. Results: VT1 was noted at 62 +/- 10% VO2peak, 75 +/- 10% HRpeak, 42 +/- 14% HRR and 47 +/- 11% W-peak, corresponding to the high intensity exercise domain (for %VO2peak and %HRpeak) or low intensity exercise domain (for %W-peak and %HRR). VT2 was noted at 84 +/- 9% VO2peak, 88 +/- 8% HRpeak, 74 +/- 15% HRR and 76 +/- 11% W-peak, corresponding to the high intensity exercise domain (for %HRR and %W-peak) or very hard exercise domain (for %HRpeak and %VO2peak). At best (when using %W-peak) in only 63% and 72% of all patients VT1 and VT2, respectively, corresponded to the same guideline-based exercise intensity domain, but this dropped to about 48% and 52% at worst (when using %HRR and %HRpeak, respectively). In particular, the patient's VO2peak related to differently elicited guideline-based exercise intensity domains (P < 0.05). Conclusion: The guideline-based exercise intensity domains for cardiovascular disease patients seem inconsistent, thus reiterating the need for adjustment.