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), oxygen uptake (VO) and cycling power output (W). The first and second ventilatory threshold (VT1 and VT2, respectively) was determined and extrapolated to %VO, %HR, %heart rate reserve (%HRR) and %W for comparison with guideline-based exercise intensity domains.

Results: VT1 was noted at 62 ± 10% VO, 75 ± 10% HR, 42 ± 14% HRR and 47 ± 11% W, corresponding to the high intensity exercise domain (for %VO and %HR) or low intensity exercise domain (for %W and %HRR). VT2 was noted at 84 ± 9% VO, 88 ± 8% HR, 74 ± 15% HRR and 76 ± 11% W, corresponding to the high intensity exercise domain (for %HRR and %W) or very hard exercise domain (for %HR and %VO). At best (when using %W) 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, respectively). In particular, the patient's VO related to differently elicited guideline-based exercise intensity domains ( < 0.05).

Conclusion: The guideline-based exercise intensity domains for cardiovascular disease patients seem inconsistent, thus reiterating the need for adjustment.