Use Of Smartphone Application Assessment Of Heart Rate Variability In Baseline Concussion Assessments Of Adolescent Student Athletes

Purpose: Heart rate variability (HRV) is a robust biomarker of health, pathology (like concussion), and athletic performance. Standard sports baseline testing fails to capture objective physiology to better inform diagnosis. Traditional HRV assessments require electrocardiography, which is often too cumbersome or costly to be completed on-field. Sensors have provided an alternative for assessing HRV. This work evaluates the use of a hardware free smartphone application to assess pre-seasons HRV metrics in student athletes. Methods: This retrospective analysis of clinical data was collected from 2021-2023 using photoplethysmography via smartphone camera light to detect volumetric changes in peripheral blood flow representing pulse-to-pulse intervals. HRV, average time between normal-to-normal (NN) heartbeat intervals (AVNN), standard deviation of NN intervals (SDNN), root mean square of successive differences (RMSSD), and the mean number of times an hour the chance in NN intervals exceeds 50 ms (PNN50) were collected continuously for 5 minutes. Descriptive statistics were used to evaluate trends in the sample. Results: 445 athletes (males = 171, females = 146, unspecified = 128), mean age 14.45 (+/- 1.66) years were evaluated. Sports included field hockey (n = 55), soccer (n = 115), tennis (n = 40), football (n = 58), water polo (n = 28), volleyball (n = 50), basketball (n = 26), ice hockey (n = 17), baseball (n = 11), other (n = 45). Male athletes demonstrated a mean HR = 84.80 ± 12.83, AVNN = 725.13 ± 111.79, SDNN = 48.85 ± 18.97, RMSSD = 41.26 ± 21.48, and PNN50 = 21.04 ± 18.37. Female athletes demonstrated a mean HR = 86.85 ± 14.81, AVNN =711.30 ± 120.74, SDNN = 51.64 ± 18.30, RMSSD = 46.38 ± 22.02, and PNN50 = 26.38 ± 19.43. Conclusions: Smartphone based HRV assessments can be used in the pre-season baseline assessment of student athletes. Future work should evaluate correlations of these metrics across sports and genders to establish a normative dataset.