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 (HR _peak ), oxygen uptake (VO _2peak ) and cycling power output (W _peak ). The first and second ventilatory threshold (VT1 and VT2, respectively) was determined and extrapolated to %VO _2peak , %HR _peak , %heart rate reserve (%HRR) and %W _peak for comparison with guideline-based exercise intensity domains.
Results: VT1 was noted at 62 ± 10% VO _2peak , 75 ± 10% HR _peak , 42 ± 14% HRR and 47 ± 11% W _peak , corresponding to the high intensity exercise domain (for %VO _2peak and %HR _peak ) or low intensity exercise domain (for %W _peak and %HRR). VT2 was noted at 84 ± 9% VO _2peak , 88 ± 8% HR _peak , 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 %HR _peak and %VO _2peak ). 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 %HR _peak , respectively). In particular, the patient's VO _2peak 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.