Does exercise prescription based on estimated heart rate training zones exceed the ventilatory anaerobic threshold in patients with coronary heart disease undergoing usual-care cardiovascular rehabilitation? : a United Kingdom perspective

Background: In the United Kingdom (UK), exercise intensity is prescribed from a fixed percentage range (% heart rate reserve; %HRR) in cardiac rehabilitation (CR) programmes. We aimed to determine the accuracy of this approach by comparing itwith an objective, threshold-based approach incorporating the accurate determination of ventilatory anaerobic threshold (VAT). We also aimed to investigate the role of baseline cardiorespiratory fitness status, and exercise testing mode dependency (cyclev treadmill ergometer) on these relationships.Design/Methods: A maximal cardiopulmonary exercise test was conducted on a cycle ergometer or a treadmill before and following usual-care circuit training from two separate CR programmes from a single region in the UK. The heart rate corresponding to VAT was compared to current heart rate-based exercise prescription guidelines.Results: We included 112 referred patients (61 years [59-63]; body mass index 29 kg∙m-2 [29-30]; 88% male). There was a significant but relatively weak correlation (r=0.32; P=0.001) between measured and predicted %HRR, and values were significantly different from each other (P=0.005). Within this cohort, we found that 54% of patients had their VAT identified outside of the 40-70% predicted HRR exercise training zone. In the majority of participants (45%), the VAT occurred at an exercise intensit