Exercise heart rate recovery: analysis of methods and call for standards

In the last several years, measures of exercise heart rate recovery (HRR) have been increasingly utilised to help assess risk and functional autonomic status in both healthy individuals and those with a wide variety of diseases. However, currently there are no national or international standards for obtaining and reporting HRR. Lack of uniformity in how HRR is obtained, analysed and reported makes comparisons between studies difficult, and hinders interpretation of results for individual subjects. This paper will review HRR methodology and promote establishing uniform standards for exercise laboratories performing the study. In order to assess current practice measuring HRR, we surveyed 74 studies that used a variety of exercise types, protocols and methods of analysis. A tally of these studies indicates that graded treadmill exercise was the preferred exercise protocol, having been used in approximately 72% of the studies, followed by cycle ergometry in 25% and other methods in 3%. In general, subjects reach a higher level of peak oxygen consumption on a treadmill than a cycle, which leads to differences in HRR between the two modes of exercise.1 In addition, there are significant differences between maximal arm and leg ergometry2 and likely between supine and upright leg ergometry.3 Despite the advantages of using a treadmill, cycle exercise will likely continue to be used, as it allows the subject to remain more stable when combining the exercise with additional studies such as myocardial imaging or echocardiography. It is therefore important to prominently note the type of exercise used when reporting HRR, including whether the subject is upright, sitting or supine. Perhaps the most important exercise variable determining HRR is the goal used for the amount of exercise achieved. Symptom limited maximal exercise is most widely used, and offers a reproducible endpoint for comparison between …