Ultra-shortened time-domain HRV parameters at rest and following exercise in athletes: an alternative to frequency computation of sympathovagal balance

• DOI: 10.1007/s00421-017-3759-x
• Publication Date: 2017-11-11T06:05:03Z
• Authors: Michael R. Esco; Henry N. Williford; Andrew A. Flatt; Todd J. Freeborn; Fabio Y. Nakamura
• Keywords: Male; Cardiovascular-autonomic control; Vagus Nerve; Kinesiology; 796; Electrocardiography; Random Allocation; Young Adult; 03 medical and health sciences; 0302 clinical medicine; Athlete monitoring; Athletes; Heart Rate; Medicine and Health Sciences; Exercise Test; Humans; RMSDD; Time-domain; Heart rate variability; Physical Conditioning, Human

The primary purpose of this study was to determine the accuracy of the standard deviation of normal-to-normal intervals (SDNN) to root mean square of successive normal-to-normal interval differences (RMSSD) ratio from 1-min recordings (SDNN:RMSSD1-min) compared to criterion recordings, as well as its relationship to low-frequency-to-high-frequency ratio (LF:HF) at rest and following maximal exercise in a group of collegiate athletes.Twenty athletes participated in the study. Heart rate variability (HRV) data were measured for 5 min before and at 5-10 and 25-30 min following a maximal exercise test. From each 5-min segment, the frequency-domain measures of HF, LF, and LF:HF ratio were analyzed. Time-domain measures of SDNN, RMSSD, and SDNN:RMSSD ratio were also analyzed from each 5-min segment, as well as from randomly selected 1-min recordings.The 1-min values of SDNN, RMSSD, and SDNN:RMSSD provided no significant differences and nearly perfect intra-class correlations (ICCs ranged from 0.97 to 1.00, p < 0.001 for all) to the criterion measures from 5-min recordings. In addition, SDNN, RMSSD, and SDNN:RMSSD from the 1-min segments provided very large to nearly perfect correlations (r values ranged from 0.71 to 0.97, p < 0.001 for all) to LF, HF, and LF:HF, respectively, at each time point.The findings of the study suggest that ultra-shortened time-domain markers may be useful surrogates of the frequency-domain parameters for tracking changes in sympathovagal activity in athletes.