%A Bourdillon,Nicolas %A Schmitt,Laurent %A Yazdani,Sasan %A Vesin,Jean-Marc %A Millet,Grégoire P. %D 2017 %J Frontiers in Neuroscience %C %F %G English %K accuracy,HRV,Fatigue,RMSSD,LF-HF,Athlete %Q %R 10.3389/fnins.2017.00456 %W %L %M %P %7 %8 2017-August-10 %9 Original Research %+ Nicolas Bourdillon,Faculty of Biology and Medicine, Institute of Sport Sciences, University of Lausanne,Lausanne, Switzerland,nicolas.bourdillon@unil.ch %# %! HRV optimal window %* %< %T Minimal Window Duration for Accurate HRV Recording in Athletes %U https://www.frontiersin.org/articles/10.3389/fnins.2017.00456 %V 11 %0 JOURNAL ARTICLE %@ 1662-453X %X Heart rate variability (HRV) is non-invasive and commonly used for monitoring responses to training loads, fitness, or overreaching in athletes. Yet, the recording duration for a series of RR-intervals varies from 1 to 15 min in the literature. The aim of the present work was to assess the minimum record duration to obtain reliable HRV results. RR-intervals from 159 orthostatic tests (7 min supine, SU, followed by 6 min standing, ST) were analyzed. Reference windows were 4 min in SU (min 3–7) and 4 min in ST (min 9–13). Those windows were subsequently divided and the analyses were repeated on eight different fractioned windows: the first min (0–1), the second min (1–2), the third min (2–3), the fourth min (3–4), the first 2 min (0–2), the last 2 min (2–4), the first 3 min (0–3), and the last 3 min (1–4). Correlation and Bland & Altman statistical analyses were systematically performed. The analysis window could be shortened to 0–2 instead of 0–4 for RMSSD only, whereas the 4-min window was necessary for LF and total power. Since there is a need for 1 min of baseline to obtain a steady signal prior the analysis window, we conclude that studies relying on RMSSD may shorten the windows to 3 min (= 1+2) in SU or seated position only and to 6 min (= 1+2 min SU plus 1+2 min ST) if there is an orthostatic test. Studies relying on time- and frequency-domain parameters need a minimum of 5 min (= 1+4) min SU or seated position only but require 10 min (= 1+4 min SU plus 1+4 min ST) for the orthostatic test.