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.