Smart phone app’s and other field tools have made HRV data collection relatively simple and affordable for coaches, athletes and recreational lifters. However, the shortened recording methodology utilized by these devices requires validation. Standardized guidelines recommend that short-term (i.e., 5-min) HRV be collected under physiologically stable conditions (Task Force). Most HRV papers will allow for 5 minutes or greater of supine rest prior to HRV recording to allow for stabilization. However, this 5+ minute pre-recording period is not practical for daily monitoring. A 1 – 2 minute HRV recording period with a very minimal stabilization period used by many app’s is still too long for some individuals to comply with daily measures.
The issue of “stabilization” was the topic of our latest research project that we just presented at the ACSM Annual Meeting in Orlando this past weekend. We looked at the time-course for stabilization of HRV across 5-min ECG segments (e.g., 0-5 min, 1-6 min, 2-7 min, 3-8 min, etc.) in 12 endurance athletes (6 female) and 12 non-athletes (6 female). We included lnHFnu, lnLFnu, and lnRMSSD.
The figures from the poster are displayed below (Athletes on left)
The full manuscript for this project (with a different methodological approach) is currently in review so I will not get into too much depth on the discussion of the results. However, it is quite clear that lnRMSSD demonstrates the most and earliest stability of the 3 HRV parameters. Therefore, for lnRMSSD assessment, a minimal stabilization period is likely a non-issue. When including spectral measures (e.g., HF, LF), a longer period for stabilization may be required, though lnHFnu was relatively stable in the athletic group in the current sample.