Influence of β-blockers on heart rate recovery and rating of perceived exertion when determining training intensity for cardiac rehabilitation

BackgroundThe influence of β-blockers on heart rate recovery (HRR) and rating of perceived exertion (RPE) during Phase I cardiac rehabilitation (CR) for patients with a recent episode of acute myocardial infarction (AMI) is not clear.MethodsFrom October 2009 to July 2011, 105 patients with a recent episode of AMI who received a successful percutaneous coronary intervention were recruited into this study. Before entering Phase II CR, each patient underwent a cardiopulmonary exercise test (CPET), where RPE was assessed every minute and related parameters were recorded.ResultsThe participants entering CR had relatively low mean peak oxygen consumption (VO2max). However, the peak heart rate and VO2max were lower in those taking β-blockers. The RPE value at the ventilatory threshold (VT) was significantly higher (12.7 ± 1.7) in participants who were taking β-blockers relative to those who were not (11.5 ± 1.4). The HRR value was lower (12.5 ± 8.8) in participants who were taking β-blockers relative to those who were not (17.0 ± 9.1).ConclusionThese findings suggest that use of β-blockers increased the RPE value at the VT. In addition, HRR was attenuated by β-blockers. In patients who do not undergo CPET, the use of β-blockers should be taken into consideration when using RPE for the initial exercise prescription to determine training intensity.