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

Background: The 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.

Methods: From 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.

Results: The 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).

Conclusion: These 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.