Levine, Benjamin D

Heart rate variability (HRV) is a widely utilized approach for investigating cardiovascular health and human performance. Methodological approaches, analyses, and interpretations of HRV can vary extensively, and scientific debates on HRV reliability and utility remain. These debates have been amplified in recent years by the rapid growth and ubiquity of wearable devices, and their incorporation into scientific research studies. The present guidelines paper takes an evidence-based approach to propose more consistent and rigorous measurement and interpretation of HRV within human cardiovascular research and application. First, HRV has some utility as a cardiovascular risk stratification tool, but is not appropriate to employ as a specific marker of cardiac sympathetic outflow or sympathovagal balance. While time-domain and spectral analysis can more accurately reflect respiratory modulation of cardiac vagal (parasympathetic) activity, caution is necessary to avoid overinterpretation, particularly with respect to the concept of “vagal tone”. Numerous experimental, demographic, and environmental factors influence HRV assessment, interpretation, and reliability. Specifically, it is critical to account for non-modifiable (age, sex, race/ethnicity, etc.) and modifiable (i.e., exercise, physical fitness, etc.) factors within participant samples. Furthermore, technical approaches such as the HRV input signal (e.g., electrocardiography vs. photoplethysmography), length of recording, location of recordings (i.e., laboratory vs. field), respiratory rate and depth, and analytical approaches (i.e., time vs. frequency domain) can all impact rigor, reliability, and study interpretations. Finally, with respect to the rapid advancements of HRV assessment using wearable technology, investigators should interpret and contextualize findings within the limitations outlined in this guideline review.

Exercise and physical activity are recognized as essential tools to optimize fitness and longevity, improve overall health, and reduce the risk of cardiovascular disease and other major comorbidities. However, there are inherent risks associated with participation in sports and exercise, regardless of the level of competition or skill required. As such, there is a need for cardiologists to understand the unique aspects of competitive and recreational athletics, as well as sport and exercise science, as it relates to overall heart health and cardiovascular risk. In this article, we provide an overview of the essential aspects of sports and exercise cardiology. We describe the roles and responsibilities of a sports and exercise cardiologist as a member of a comprehensive team of experts who provide care of athletes at all levels of sport, emphasize the importance of risk stratification and prevention of sudden cardiac arrest, the role of exercise for maintaining and optimizing overall health in the general population, describe the growing field of sports electrophysiology and also discuss unique aspects of sports cardiology applied to environmental health and care of the tactical athlete. Knowledge gaps and directions for future clinical and research investigation are reviewed.