Mobile Evaluation of Heart Rate Variability Using the Diver's Reflex

Introduction. Heart rate variability (HRV) is considered a marker of autonomic nervous system (ANS) function and a biomarker of interest in evaluating nervous system function following traumatic brain injury. This study validates prior research with larger sample sizes and proposes a model for establishing baseline HRV reactivity in healthy participants. Methods. Sixty-two healthy collegiate athletes were recruited for this study. Following informed consent, they were evaluated supine using the Elite HRV CorSense monitor and platform to record low frequency/high frequency (LF/HF) ratio and root means square of successive differences (RMSSD) over 5 min. A bag of ice was placed on their face, then RMSSD and LF/HF ratio were collected over three successive 1-min intervals. Results. RMSSD was elevated at 1 and 2 min (+47.4 ms, p < .0001; +16.5 ms, p = .014) following face cooling and fell to baseline at 3 min (+4.6 ms, p = .52). LF/HF ratio decreased following face cooling at 2 and 3 min (change from rest %: 2 min, −33%, p = .007; 3 min, −50%, p = < .0001). Conclusion. The Elite HRV platform can detect an elevation in RMSSD in the first minute following face cooling with a return to baseline in the second and third minutes. It can also detect a consistent decrease in LF/HF following face cooling.