Heart rate variability as a measure of autonomic regulation of cardiac activity during mental stress

Abstract

The purpose of the study was to investigate heart rate variability (HRV) parameters during mental arithmetic stress. Material and methods. One hundred fifty healthy students with a mean age of 20.56±0.17 years were enrolled in the study. HRV parameters were analyzed using linear (time domain and frequency domain) and nonlinear methods. Nonlinear analysis of HRV was performed by using Poincare plot parameters (SD1, SD2, SD1/SD2, SS), complex correlation measure (CCM), Sample Entropy and detrended fluctuation analysis. HRV parameters were recording at rest (10 minutes) and during mental arithmetic (10 minutes). Results. Time domain parameters were significantly reduce during mental stress. HF and SD1 were significantly lower during the mental arithmetic condition than that at rest. SD1/SD2 ratio and SS also decreased more during mental stress (0,46±0,02 vs 0,34±0,01 and 8553,18±873,70 vs 6219,83±692,50; p<0,001). VLF and pLF were higher during stress than that at rest (1122,18±75,35 vs 1460,75±86,53 and 49,28±1,36 vs 56,49±1,05; p<0,001). CCM and SampEn parameters were significantly lower during the test than that at rest (0,15±0,01 vs 0,21±0,01; p<0.001; 1,34±0,03 vs 1,59±0,02; p<0,0001). Alpha, alpha1 and alpha2 were higher during stress than that at rest (0,92±0,01 vs 0,84±0,01; 1,11±0,02 vs 0,98±0,02 and 0,92±0,01 vs 0,84±0,01; p<0,01). Conclusions The results of the current study suggest that HRV analysis could be effective in automatically detecting functional state during mental stress. This work was supported by the Ministry of Education (№1404).