Journal of Health & Medical Informatics

Background/Rationale: Photoplethysmography (PPG) may enable large-scale, accurate and cost-effective measurement of Pulse Rate Variability (PRV) as a surrogate for Heart Rate Variability (HRV) to inform real-world training of athletes. A significant body of research has investigated HRV as a non-invasive composite measure of cardio-autonomic function with application to exercise interventions and training protocols for athletes and athletics. However, the rapidity of commercialization of PPG-based wearables raises the question of what clinical research exists to enable realworld usage analogous to HRV-based wearables. PPG from wearable devices is a fundamentally different technology than the Electrocardiogram (ECG). Similarly, HRV and distally measured PRV may represent different underlying physiological processes or time courses.

Aim: Perform a literature search of all exercise, athletic training, and athletic performance research using commercial wearable devices with PPG.

Methods/Conclusions: The major gap in understanding of PRV measurement is how to use results to inform real-world training protocols and interventions. Few papers were found evaluating PRV measured by PPG technology for athletes, exercise, or training recommendations. Over half of the literature search findings are devoted to custom devices/software or would be difficult to replicate for field usage. Only a few studies examined PRV over time periods necessary for training adaptations and no studies were identified that tested varied exercise protocol micro/ macro-cycles. We recommend both more clinical studies of PRV from PPG technology to stratify underlying physiological mechanisms of value for athletics, and real-world studies to inform progressive exercise training methods and benefits/limitations of PRV outside of the clinical lab.